Update whatsnew/3.4 wrt. --version going to stdout. #18338, #18920, #18922

Doc/whatsnew/3.4.rst

@@ -428,6 +428,13 @@ Tab-completion is now enabled by default in the interactive interpreter.
 
 (Contributed by Antoine Pitrou and Éric Araujo in :issue:`5845`.)
 
+Python invocation changes
+=========================
+
+Invoking the Python interpreter with ``--version`` now outputs the version to
+standard output instead of standard error (:issue:`18338`). Similar changes
+were made to :mod:`argparse` (:issue:`18920`) and other modules that have
+script-like invocation capabilities (:issue:`18922`).
 
 Optimizations
 =============