gh-129846: clarify suppression of warning output in catch_warnings

Doc/library/warnings.rst

@@ -623,10 +623,13 @@ Available Context Managers
 
     A context manager that copies and, upon exit, restores the warnings filter
     and the :func:`showwarning` function.
-    If the *record* argument is :const:`False` (the default) the context manager
-    returns :class:`None` on entry. If *record* is :const:`True`, a list is
-    returned that is progressively populated with objects as seen by a custom
-    :func:`showwarning` function (which also suppresses output to ``sys.stdout``).
+
+    If the *record* argument is false (the default) the context manager
+    returns ``None`` on entry.
+    If *record* is true, the :func:`showwarning` function is temporarily reset
+    to the default implementation and a list is returned that is progressively
+    populated with objects as seen by the :func:`!showwarning` function
+    (which also suppresses output to ``sys.stderr`` and other streams).
     Each object in the list has attributes with the same names as the arguments to
     :func:`showwarning`.