filters: Modernize the docs

Remove gtk-docisms, apply more gi-docgen syntax, and reword things
to be closer to the style recommended in

https://developer.gnome.org/documentation/guidelines/devel-docs.html
diff --git a/gtk/gtkboolfilter.c b/gtk/gtkboolfilter.c
index b35ebed..dca433c 100644
--- a/gtk/gtkboolfilter.c
+++ b/gtk/gtkboolfilter.c
@@ -26,8 +26,7 @@
 /**
  * GtkBoolFilter:
  *
- * `GtkBoolFilter` evaluates a boolean `GtkExpression`
- * to determine whether to include items.
+ * Evaluates a boolean expression to determine whether to include items.
  */
 
 struct _GtkBoolFilter
@@ -155,7 +154,7 @@
   /**
    * GtkBoolFilter:expression: (type GtkExpression)
    *
-   * The boolean expression to evaluate on item.
+   * The boolean expression to evaluate on each item.
    */
   properties[PROP_EXPRESSION] =
     gtk_param_spec_expression ("expression", NULL, NULL,
@@ -181,7 +180,7 @@
 
 /**
  * gtk_bool_filter_new:
- * @expression: (transfer full) (nullable): The expression to evaluate
+ * @expression: (transfer full) (nullable): the expression to evaluate
  *
  * Creates a new bool filter.
  *
@@ -203,12 +202,12 @@
 
 /**
  * gtk_bool_filter_get_expression:
- * @self: a `GtkBoolFilter`
+ * @self: a bool filter
  *
- * Gets the expression that the filter uses to evaluate if
- * an item should be filtered.
+ * Gets the expression that the filter evaluates for
+ * each item.
  *
- * Returns: (transfer none) (nullable): a `GtkExpression`
+ * Returns: (transfer none) (nullable): the expression
  */
 GtkExpression *
 gtk_bool_filter_get_expression (GtkBoolFilter *self)
@@ -220,13 +219,13 @@
 
 /**
  * gtk_bool_filter_set_expression:
- * @self: a `GtkBoolFilter`
- * @expression: (nullable): a `GtkExpression`
+ * @self: a bool filter
+ * @expression: (nullable): the expression
  *
  * Sets the expression that the filter uses to check if items
  * should be filtered.
  *
- * The expression must have a value type of %G_TYPE_BOOLEAN.
+ * The expression must have a value type of `G_TYPE_BOOLEAN`.
  */
 void
 gtk_bool_filter_set_expression (GtkBoolFilter *self,
@@ -249,11 +248,11 @@
 
 /**
  * gtk_bool_filter_get_invert:
- * @self: a `GtkBoolFilter`
+ * @self: a bool filter
  *
  * Returns whether the filter inverts the expression.
  *
- * Returns: %TRUE if the filter inverts
+ * Returns: true if the filter inverts
  */
 gboolean
 gtk_bool_filter_get_invert (GtkBoolFilter *self)
@@ -265,8 +264,8 @@
 
 /**
  * gtk_bool_filter_set_invert:
- * @self: a `GtkBoolFilter`
- * @invert: %TRUE to invert
+ * @self: a bool filter
+ * @invert: true to invert
  *
  * Sets whether the filter should invert the expression.
  */
diff --git a/gtk/gtkcustomfilter.c b/gtk/gtkcustomfilter.c
index 4dbd4a6..e06e463 100644
--- a/gtk/gtkcustomfilter.c
+++ b/gtk/gtkcustomfilter.c
@@ -26,7 +26,7 @@
 /**
  * GtkCustomFilter:
  *
- * `GtkCustomFilter` determines whether to include items with a callback.
+ * Determines whether to include items with a callback.
  */
 struct _GtkCustomFilter
 {
@@ -96,13 +96,12 @@
  * @user_data: (nullable): user data to pass to @match_func
  * @user_destroy: destroy notify for @user_data
  *
- * Creates a new filter using the given @match_func to filter
- * items.
+ * Creates a new filter using the given function to filter items.
  *
- * If @match_func is %NULL, the filter matches all items.
+ * If @match_func is `NULL`, the filter matches all items.
  *
  * If the filter func changes its filtering behavior,
- * gtk_filter_changed() needs to be called.
+ * [method@Gtk.Filter.changed] needs to be called.
  *
  * Returns: a new `GtkCustomFilter`
  **/
@@ -122,20 +121,20 @@
 
 /**
  * gtk_custom_filter_set_filter_func:
- * @self: a `GtkCustomFilter`
+ * @self: a custom filter
  * @match_func: (nullable): function to filter items
  * @user_data: (nullable): user data to pass to @match_func
  * @user_destroy: destroy notify for @user_data
  *
  * Sets the function used for filtering items.
  *
- * If @match_func is %NULL, the filter matches all items.
+ * If @match_func is `NULL`, the filter matches all items.
  *
  * If the filter func changes its filtering behavior,
- * gtk_filter_changed() needs to be called.
+ * [method@Gtk.Filter.changed] needs to be called.
  *
- * If a previous function was set, its @user_destroy will be
- * called now.
+ * If a previous function was set, its @user_destroy
+ * will be called.
  */
 void
 gtk_custom_filter_set_filter_func (GtkCustomFilter     *self,
diff --git a/gtk/gtkcustomfilter.h b/gtk/gtkcustomfilter.h
index 08d5161..49206d5 100644
--- a/gtk/gtkcustomfilter.h
+++ b/gtk/gtkcustomfilter.h
@@ -29,15 +29,15 @@
 
 /**
  * GtkCustomFilterFunc:
- * @item: (type GObject): The item to be matched
+ * @item: (type GObject): the item to be matched
  * @user_data: user data
  *
  * User function that is called to determine if the @item should be matched.
  *
- * If the filter matches the item, this function must return %TRUE. If the
- * item should be filtered out, %FALSE must be returned.
+ * If the filter matches the item, this function must return true.
+ * If the item should be filtered out, false must be returned.
  *
- * Returns: %TRUE to keep the item around
+ * Returns: true to keep the item around
  */
 typedef gboolean (* GtkCustomFilterFunc) (gpointer item, gpointer user_data);
 
diff --git a/gtk/gtkfilefilter.c b/gtk/gtkfilefilter.c
index 71f45ef..b5025b0 100644
--- a/gtk/gtkfilefilter.c
+++ b/gtk/gtkfilefilter.c
@@ -19,10 +19,10 @@
 /**
  * GtkFileFilter:
  *
- * `GtkFileFilter` filters files by name or mime type.
+ * Filters files by name or mime type.
  *
  * `GtkFileFilter` can be used to restrict the files being shown in a
- * `GtkFileChooser`. Files can be filtered based on their name (with
+ * file chooser. Files can be filtered based on their name (with
  * [method@Gtk.FileFilter.add_pattern] or [method@Gtk.FileFilter.add_suffix])
  * or on their mime type (with [method@Gtk.FileFilter.add_mime_type]).
  *
@@ -32,8 +32,8 @@
  * text/plain. Note that `GtkFileFilter` allows wildcards for the
  * subtype of a mime type, so you can e.g. filter for image/\*.
  *
- * Normally, file filters are used by adding them to a `GtkFileChooser`
- * (see [method@Gtk.FileChooser.add_filter]), but it is also possible to
+ * Normally, file filters are used by adding them to a file chooser
+ * (see [method@Gtk.FileDialog.set_filters]), but it is also possible to
  * manually use a file filter on any [class@Gtk.FilterListModel] containing
  * `GFileInfo` objects.
  *
@@ -259,8 +259,8 @@
    *
    * The human-readable name of the filter.
    *
-   * This is the string that will be displayed in the file chooser
-   * user interface if there is a selectable list of filters.
+   * This is the string that will be displayed in the user interface
+   * if there is a selectable list of filters.
    */
   props[PROP_NAME] =
       g_param_spec_string ("name", NULL, NULL,
@@ -534,13 +534,12 @@
 
 /**
  * gtk_file_filter_set_name:
- * @filter: a `GtkFileFilter`
- * @name: (nullable): the human-readable-name for the filter, or %NULL
- *   to remove any existing name.
+ * @filter: a file filter
+ * @name: (nullable): the human-readable name for the filter
  *
  * Sets a human-readable name of the filter.
  *
- * This is the string that will be displayed in the file chooser
+ * This is the string that will be displayed in the user interface
  * if there is a selectable list of filters.
  */
 void
@@ -560,13 +559,13 @@
 
 /**
  * gtk_file_filter_get_name:
- * @filter: a `GtkFileFilter`
+ * @filter: a file filter
  *
  * Gets the human-readable name for the filter.
  *
  * See [method@Gtk.FileFilter.set_name].
  *
- * Returns: (nullable): The human-readable name of the filter
+ * Returns: (nullable): the human-readable name of the filter
  */
 const char *
 gtk_file_filter_get_name (GtkFileFilter *filter)
@@ -607,10 +606,10 @@
 
 /**
  * gtk_file_filter_add_mime_type:
- * @filter: A `GtkFileFilter`
+ * @filter: A file filter
  * @mime_type: name of a MIME type
  *
- * Adds a rule allowing a given mime type to @filter.
+ * Adds a rule allowing a given mime type.
  */
 void
 gtk_file_filter_add_mime_type (GtkFileFilter *filter,
@@ -632,10 +631,10 @@
 
 /**
  * gtk_file_filter_add_pattern:
- * @filter: a `GtkFileFilter`
- * @pattern: a shell style glob
+ * @filter: a file filter
+ * @pattern: a shell style glob pattern
  *
- * Adds a rule allowing a shell style glob to a filter.
+ * Adds a rule allowing a shell style glob pattern.
  *
  * Note that it depends on the platform whether pattern
  * matching ignores case or not. On Windows, it does, on
@@ -660,13 +659,12 @@
 
 /**
  * gtk_file_filter_add_suffix:
- * @filter: a `GtkFileFilter`
+ * @filter: a file filter
  * @suffix: filename suffix to match
  *
  * Adds a suffix match rule to a filter.
  *
- * This is similar to adding a match for the pattern
- * "*.@suffix".
+ * This is similar to adding a match for the pattern "*.@suffix".
  *
  * In contrast to pattern matches, suffix matches
  * are *always* case-insensitive.
@@ -692,10 +690,9 @@
 
 /**
  * gtk_file_filter_add_pixbuf_formats:
- * @filter: a `GtkFileFilter`
+ * @filter: a file filter
  *
- * Adds a rule allowing image files in the formats supported
- * by GdkPixbuf.
+ * Adds a rule allowing image files in the formats supported by `GdkPixbuf`.
  *
  * This is equivalent to calling [method@Gtk.FileFilter.add_mime_type]
  * for all the supported mime types.
@@ -739,14 +736,13 @@
 
 /**
  * gtk_file_filter_get_attributes:
- * @filter: a `GtkFileFilter`
+ * @filter: a file filter
  *
  * Gets the attributes that need to be filled in for the `GFileInfo`
  * passed to this filter.
  *
  * This function will not typically be used by applications;
- * it is intended principally for use in the implementation
- * of `GtkFileChooser`.
+ * it is intended for use in file chooser implementation.
  *
  * Returns: (transfer none): the attributes
  */
@@ -956,7 +952,7 @@
 
 /**
  * gtk_file_filter_to_gvariant:
- * @filter: a `GtkFileFilter`
+ * @filter: a file filter
  *
  * Serialize a file filter to an `a{sv}` variant.
  *
diff --git a/gtk/gtkfilter.c b/gtk/gtkfilter.c
index 0a1c5b4..74d9262 100644
--- a/gtk/gtkfilter.c
+++ b/gtk/gtkfilter.c
@@ -27,12 +27,11 @@
 /**
  * GtkFilter:
  *
- * A `GtkFilter` object describes the filtering to be performed by a
- * [class@Gtk.FilterListModel].
+ * Describes the filtering to be performed by a [class@Gtk.FilterListModel].
  *
  * The model will use the filter to determine if it should include items
  * or not by calling [method@Gtk.Filter.match] for each item and only
- * keeping the ones that the function returns %TRUE for.
+ * keeping the ones that the function returns true for.
  *
  * Filters may change what items they match through their lifetime. In that
  * case, they will emit the [signal@Gtk.Filter::changed] signal to notify
@@ -81,7 +80,7 @@
 
   /**
    * GtkFilter::changed:
-   * @self: The `GtkFilter`
+   * @self: the filter
    * @change: how the filter changed
    *
    * Emitted whenever the filter changed.
@@ -116,13 +115,12 @@
 
 /**
  * gtk_filter_match:
- * @self: a `GtkFilter`
+ * @self: a filter
  * @item: (type GObject) (transfer none): The item to check
  *
  * Checks if the given @item is matched by the filter or not.
  *
- * Returns: %TRUE if the filter matches the item and a filter model should
- *   keep it, %FALSE if not.
+ * Returns: true if the filter matches the item
  */
 gboolean
 gtk_filter_match (GtkFilter *self,
@@ -136,16 +134,16 @@
 
 /**
  * gtk_filter_get_strictness:
- * @self: a `GtkFilter`
+ * @self: a filter
  *
- * Gets the known strictness of @filters.
+ * Gets the known strictness of a filter.
  *
- * If the strictness is not known, %GTK_FILTER_MATCH_SOME is returned.
+ * If the strictness is not known, [enum@Gtk.FilterMatch.some] is returned.
  *
  * This value may change after emission of the [signal@Gtk.Filter::changed]
  * signal.
  *
- * This function is meant purely for optimization purposes, filters can
+ * This function is meant purely for optimization purposes. Filters can
  * choose to omit implementing it, but `GtkFilterListModel` uses it.
  *
  * Returns: the strictness of @self
@@ -160,8 +158,8 @@
 
 /**
  * gtk_filter_changed:
- * @self: a `GtkFilter`
- * @change: How the filter changed
+ * @self: a filter
+ * @change: how the filter changed
  *
  * Notifies all users of the filter that it has changed.
  *
@@ -184,4 +182,3 @@
 
   g_signal_emit (self, signals[CHANGED], 0, change);
 }
-
diff --git a/gtk/gtkfilter.h b/gtk/gtkfilter.h
index 140ba14..eee00b9 100644
--- a/gtk/gtkfilter.h
+++ b/gtk/gtkfilter.h
@@ -30,16 +30,16 @@
 /**
  * GtkFilterMatch:
  * @GTK_FILTER_MATCH_SOME: The filter matches some items,
- *   gtk_filter_match() may return %TRUE or %FALSE
+ *   [method@Gtk.Filter.match] may return true or false
  * @GTK_FILTER_MATCH_NONE: The filter does not match any item,
- *   gtk_filter_match() will always return %FALSE.
+ *   [method@Gtk.Filter.match] will always return false
  * @GTK_FILTER_MATCH_ALL: The filter matches all items,
- *   gtk_filter_match() will alays return %TRUE.
+ *   [method@Gtk.Filter.match] will alays return true
  *
  * Describes the known strictness of a filter.
  *
  * Note that for filters where the strictness is not known,
- * %GTK_FILTER_MATCH_SOME is always an acceptable value,
+ * `GTK_FILTER_MATCH_SOME` is always an acceptable value,
  * even if a filter does match all or no items.
  */
 typedef enum {
@@ -51,19 +51,19 @@
 /**
  * GtkFilterChange:
  * @GTK_FILTER_CHANGE_DIFFERENT: The filter change cannot be
- *   described with any of the other enumeration values.
+ *   described with any of the other enumeration values
  * @GTK_FILTER_CHANGE_LESS_STRICT: The filter is less strict than
- *   it was before: All items that it used to return %TRUE for
- *   still return %TRUE, others now may, too.
+ *   it was before: All items that it used to return true
+ *   still return true, others now may, too.
  * @GTK_FILTER_CHANGE_MORE_STRICT: The filter is more strict than
- *   it was before: All items that it used to return %FALSE for
- *   still return %FALSE, others now may, too.
+ *   it was before: All items that it used to return false
+ *   still return false, others now may, too.
  *
  * Describes changes in a filter in more detail and allows objects
  * using the filter to optimize refiltering items.
  *
  * If you are writing an implementation and are not sure which
- * value to pass, %GTK_FILTER_CHANGE_DIFFERENT is always a correct
+ * value to pass, `GTK_FILTER_CHANGE_DIFFERENT` is always a correct
  * choice.
  */
 typedef enum {
diff --git a/gtk/gtkmultifilter.c b/gtk/gtkmultifilter.c
index da44510..41bf720 100644
--- a/gtk/gtkmultifilter.c
+++ b/gtk/gtkmultifilter.c
@@ -36,13 +36,13 @@
 /**
  * GtkMultiFilter:
  *
- * `GtkMultiFilter` is the base class for filters that combine multiple filters.
+ * Base class for filters that combine multiple filters.
  */
 
 /**
  * GtkAnyFilter:
  *
- * `GtkAnyFilter` matches an item when at least one of its filters matches.
+ * Matches an item when at least one of its filters matches.
  *
  * To add filters to a `GtkAnyFilter`, use [method@Gtk.MultiFilter.append].
  */
@@ -50,7 +50,7 @@
 /**
  * GtkEveryFilter:
  *
- * `GtkEveryFilter` matches an item when each of its filters matches.
+ * Matches an item when each of its filters matches.
  *
  * To add filters to a `GtkEveryFilter`, use [method@Gtk.MultiFilter.append].
  */
@@ -200,10 +200,12 @@
   /**
    * GtkMultiFilter:item-type:
    *
-   * The type of items. See [method@Gio.ListModel.get_item_type].
+   * The type of items.
+   *
+   * See [method@Gio.ListModel.get_item_type].
    *
    * Since: 4.8
-   **/
+   */
   properties[PROP_ITEM_TYPE] =
     g_param_spec_gtype ("item-type", NULL, NULL,
                         GTK_TYPE_FILTER,
@@ -212,10 +214,12 @@
   /**
    * GtkMultiFilter:n-items:
    *
-   * The number of items. See [method@Gio.ListModel.get_n_items].
+   * The number of items.
+   *
+   * See [method@Gio.ListModel.get_n_items].
    *
    * Since: 4.8
-   **/
+   */
   properties[PROP_N_ITEMS] =
     g_param_spec_uint ("n-items", NULL, NULL,
                        0, G_MAXUINT, 0,
@@ -232,10 +236,10 @@
 
 /**
  * gtk_multi_filter_append:
- * @self: a `GtkMultiFilter`
- * @filter: (transfer full): A new filter to use
+ * @self: a multi filter
+ * @filter: (transfer full): a filter to add
  *
- * Adds a @filter to @self to use for matching.
+ * Adds a filter.
  */
 void
 gtk_multi_filter_append (GtkMultiFilter *self,
@@ -255,14 +259,13 @@
 
 /**
  * gtk_multi_filter_remove:
- * @self: a `GtkMultiFilter`
+ * @self: a multi filter
  * @position: position of filter to remove
  *
- * Removes the filter at the given @position from the list of filters used
- * by @self.
+ * Removes a filter.
  *
- * If @position is larger than the number of filters, nothing happens and
- * the function returns.
+ * If @position is larger than the number of filters,
+ * nothing happens.
  **/
 void
 gtk_multi_filter_remove (GtkMultiFilter *self,
diff --git a/gtk/gtkstringfilter.c b/gtk/gtkstringfilter.c
index 20ee042..6b4b669 100644
--- a/gtk/gtkstringfilter.c
+++ b/gtk/gtkstringfilter.c
@@ -26,10 +26,9 @@
 /**
  * GtkStringFilter:
  *
- * `GtkStringFilter` determines whether to include items by comparing
- * strings to a fixed search term.
+ * Determines whether to include items by comparing strings to a fixed search term.
  *
- * The strings are obtained from the items by evaluating a `GtkExpression`
+ * The strings are obtained from the items by evaluating an expression
  * set with [method@Gtk.StringFilter.set_expression], and they are
  * compared against a search term set with [method@Gtk.StringFilter.set_search].
  *
@@ -249,7 +248,8 @@
   /**
    * GtkStringFilter:expression: (type GtkExpression)
    *
-   * The expression to evaluate on item to get a string to compare with.
+   * The expression to evaluate on each item to get a
+   * string to compare with.
    */
   properties[PROP_EXPRESSION] =
     gtk_param_spec_expression ("expression", NULL, NULL,
@@ -299,7 +299,7 @@
 
 /**
  * gtk_string_filter_new:
- * @expression: (transfer full) (nullable): The expression to evaluate
+ * @expression: (transfer full) (nullable): the expression to evaluate
  *
  * Creates a new string filter.
  *
@@ -324,11 +324,11 @@
 
 /**
  * gtk_string_filter_get_search:
- * @self: a `GtkStringFilter`
+ * @self: a string filter
  *
  * Gets the search term.
  *
- * Returns: (nullable) (transfer none): The search term
+ * Returns: (nullable) (transfer none): the search term
  **/
 const char *
 gtk_string_filter_get_search (GtkStringFilter *self)
@@ -340,9 +340,8 @@
 
 /**
  * gtk_string_filter_set_search:
- * @self: a `GtkStringFilter`
- * @search: (transfer none) (nullable): The string to search for
- *   or %NULL to clear the search
+ * @self: a string filter
+ * @search: (transfer none) (nullable): the string to search for
  *
  * Sets the string to search for.
  */
@@ -381,12 +380,12 @@
 
 /**
  * gtk_string_filter_get_expression:
- * @self: a `GtkStringFilter`
+ * @self: a string filter
  *
  * Gets the expression that the string filter uses to
  * obtain strings from items.
  *
- * Returns: (transfer none) (nullable): a `GtkExpression`
+ * Returns: (transfer none) (nullable): the expression 
  */
 GtkExpression *
 gtk_string_filter_get_expression (GtkStringFilter *self)
@@ -398,13 +397,13 @@
 
 /**
  * gtk_string_filter_set_expression:
- * @self: a `GtkStringFilter`
- * @expression: (nullable): a `GtkExpression`
+ * @self: a string filter
+ * @expression: (nullable): the expression
  *
  * Sets the expression that the string filter uses to
  * obtain strings from items.
  *
- * The expression must have a value type of %G_TYPE_STRING.
+ * The expression must have a value type of `G_TYPE_STRING`.
  */
 void
 gtk_string_filter_set_expression (GtkStringFilter *self,
@@ -427,11 +426,11 @@
 
 /**
  * gtk_string_filter_get_ignore_case:
- * @self: a `GtkStringFilter`
+ * @self: a string filter
  *
  * Returns whether the filter ignores case differences.
  *
- * Returns: %TRUE if the filter ignores case
+ * Returns: true if the filter ignores case
  */
 gboolean
 gtk_string_filter_get_ignore_case (GtkStringFilter *self)
@@ -443,8 +442,8 @@
 
 /**
  * gtk_string_filter_set_ignore_case:
- * @self: a `GtkStringFilter`
- * @ignore_case: %TRUE to ignore case
+ * @self: a string filter
+ * @ignore_case: true to ignore case
  *
  * Sets whether the filter ignores case differences.
  */
@@ -471,7 +470,7 @@
 
 /**
  * gtk_string_filter_get_match_mode:
- * @self: a `GtkStringFilter`
+ * @self: a string filter
  *
  * Returns the match mode that the filter is using.
  *
@@ -487,7 +486,7 @@
 
 /**
  * gtk_string_filter_set_match_mode:
- * @self: a `GtkStringFilter`
+ * @self: a string filter
  * @mode: the new match mode
  *
  * Sets the match mode for the filter.
diff --git a/gtk/gtkstringfilter.h b/gtk/gtkstringfilter.h
index 1ed070a..55119de 100644
--- a/gtk/gtkstringfilter.h
+++ b/gtk/gtkstringfilter.h
@@ -31,11 +31,11 @@
 /**
  * GtkStringFilterMatchMode:
  * @GTK_STRING_FILTER_MATCH_MODE_EXACT: The search string and
- *   text must match exactly.
+ *   text must match exactly
  * @GTK_STRING_FILTER_MATCH_MODE_SUBSTRING: The search string
- *   must be contained as a substring inside the text.
+ *   must be contained as a substring inside the text
  * @GTK_STRING_FILTER_MATCH_MODE_PREFIX: The text must begin
- *   with the search string.
+ *   with the search string
  *
  * Specifies how search strings are matched inside text.
  */