trunc -> math.trunc (closes #11475)

Doc/library/numbers.rst

diff --git a/Doc/library/numbers.rst b/Doc/library/numbers.rst
index 67c2f33..df8d521 100644
--- a/Doc/library/numbers.rst
+++ b/Doc/library/numbers.rst
@@ -45,7 +45,7 @@
    To :class:`Complex`, :class:`Real` adds the operations that work on real
    numbers.
 
-   In short, those are: a conversion to :class:`float`, :func:`trunc`,
+   In short, those are: a conversion to :class:`float`, :func:`math.trunc`,
    :func:`round`, :func:`math.floor`, :func:`math.ceil`, :func:`divmod`, ``//``,
    ``%``, ``<``, ``<=``, ``>``, and ``>=``.