3.9
[3.9] gh-121277: Allow .. versionadded:: next in docs (GH-121278) (#128117)
bpo-41028: Doc: Move switchers to docsbuild-scripts. (GH-20969) (GH-30343)
bpo-11233: Create availability directive for documentation (GH-9692)
[3.9] gh-113171: gh-65056: Fix "private" (non-global) IP address ranges (GH-113179) (GH-113186) (GH-118177) (GH-118472)