whatsnew for gc.get_stats, plus doc tweaks.

Clarified the "At the moment" wording, and added the get_stats entry in the
module summary that Serhiy noted was missing at the end of issue 16351.

Given that pydoc lists all the function docstrings, I'm not sure that module
summary section is actually needed; but, it is probably better to address that
when the module is converted to use Argument Clinic.  In the meantime we
should keep the list complete.

1 files changed, 4 insertions, 3 deletions

diff --git a/Doc/library/gc.rst b/Doc/library/gc.rst
index 6b95dc5..8135542 100644
--- a/Doc/library/gc.rst
+++ b/Doc/library/gc.rst
@@ -69,9 +69,10 @@ The :mod:`gc` module provides the following functions:
 
 .. function:: get_stats()
 
-   Return a list of 3 per-generation dictionaries containing collection
-   statistics since interpreter start.  At this moment, each dictionary will
-   contain the following items:
+   Return a list of three per-generation dictionaries containing collection
+   statistics since interpreter start.  The number of keys may change
+   in the future, but currently each dictionary will contain the following
+   items:
 
    * ``collections`` is the number of times this generation was collected;