gh-95914: Add Py_UNICODE encode APIs removed in PEP 624 to 3.11 What's New (GH-96016)

* 3.11 Whatsnew: Add Py_UNICODE encode functions removed in PEP 624

* Just use :func: instead of :c:func: for non-resolved funcs so ! works
(cherry picked from commit b6d88b7225c36821845d4ba1312a6d6b2f7f65c8)

Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>