[3.12] GH-115986 Reorder pprint docs and amend some references (GH-116019) (#116061)

GH-115986 Reorder pprint docs and amend some references (GH-116019)

Introduce a new subsubsection, 'Functions', for module level functions,
and place it before the PrettyPrinter class reference.

Also:
- Fix pprint.pprint() references so they properly link to the module
  level function.
- Add links to sys.stdout.
(cherry picked from commit 6c1c94dc517b77afcebb25436a4b7b0d13b6eb4d)

Co-authored-by: Kerim Kabirov <39376984+Privat33r-dev@users.noreply.github.com>