gh-95913: Copyedit, xref and organize enum section (GH-98295)

* Whatsnew: Convert literals in enum section to actual x-references

* Whatsnew: Rewrite enum section for clear and consistant phrasing

* Whatsnew: Combine directly related enum items instead of seperating them

* gh-98250: Describe __str__/__format__ changes more clearly/accurately

* Tweak enum section language per feedback from Ethan
(cherry picked from commit 73e5180faf37e2d362e13f4ef12955a8b8535d7b)

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