add note regarding datetime docs (#72976)

Adds a note pointing to the datetime documentation as to_datetime does not use the time library but instead uses datetime.
Co-authored-by: Alicia Cozine <879121+acozine@users.noreply.github.com>

docs/docsite/rst/user_guide/playbooks_filters.rst

@@ -1660,6 +1660,8 @@ To get a date object from a string use the `to_datetime` filter::
 
     # get amount of days between two dates. This returns only number of days and discards remaining hours, minutes, and seconds
     {{ (("2016-08-14 20:00:12" | to_datetime) - ("2015-12-25" | to_datetime('%Y-%m-%d'))).days  }}
+    
+.. note:: For a full list of format codes for working with python date format strings, see https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior.
 
 .. versionadded:: 2.4