[animations] Clarify that onClosed is called before transition (#10400)

Updated the documentation for `OpenContainer.onClosed` to clarify that it is called at the start of the closing transition, not at the end.

Resolves https://github.com/flutter/flutter/issues/178314

## Pre-Review Checklist

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[^1]: This PR only affects comments/documentation.

packages/animations/CHANGELOG.md

diff --git a/packages/animations/CHANGELOG.md b/packages/animations/CHANGELOG.md
index c4a7544..4cb0aed 100644
--- a/packages/animations/CHANGELOG.md
+++ b/packages/animations/CHANGELOG.md
@@ -1,5 +1,6 @@
-## NEXT
+## 2.1.1
 
+* Updated the documentation for `OpenContainer.onClosed` to clarify that it is called at the start of the closing transition, not at the end.
 * Updates minimum supported SDK version to Flutter 3.32/Dart 3.8.
 
 ## 2.1.0

packages/animations/lib/src/open_container.dart

diff --git a/packages/animations/lib/src/open_container.dart b/packages/animations/lib/src/open_container.dart
index 7416ab7..56b3446 100644
--- a/packages/animations/lib/src/open_container.dart
+++ b/packages/animations/lib/src/open_container.dart
@@ -190,7 +190,8 @@
   ///  * [Material.shape], which is used to implement this property.
   final ShapeBorder openShape;
 
-  /// Called when the container was popped and has returned to the closed state.
+  /// Called when the container is popped. This is called at the start of the
+  /// closing transition.
   ///
   /// The return value from the popped screen is passed to this function as an
   /// argument.

packages/animations/pubspec.yaml

diff --git a/packages/animations/pubspec.yaml b/packages/animations/pubspec.yaml
index 15be5e1..40509a2 100644
--- a/packages/animations/pubspec.yaml
+++ b/packages/animations/pubspec.yaml
@@ -2,7 +2,7 @@
 description: Fancy pre-built animations that can easily be integrated into any Flutter application.
 repository: https://github.com/flutter/packages/tree/main/packages/animations
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+animations%22
-version: 2.1.0
+version: 2.1.1
 
 environment:
   sdk: ^3.8.0