Issue #16574: Clarify that once a PEP has implemented, it needs be documented in Python docs.
Issue #16574: Clarify that once a PEP has implemented, it needs be
documented in Python docs.

Patch by Carol Willing. Wording suggested by Terry J. Reedy.

jeff5/jython-devguide,jython/devguide,ezio-melotti/devguide,jython/devguide,jython/devguide,jeff5/jython-devguide,jeff5/jython-devguide