[3.12] gh-129712: Document the wheels tags corresponding to each universal SDK. (GH-130389) (#130450)

Document the architectures supported by macOS universal SDK configuration flags,
and add details on wheel tag naming.
(cherry picked from commit 474c388740ca5f8060c074f517dd14c54409126f)

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>