Add docs for `enum.bin`

[guoci]

Documentation

Add docs for enum.bin, as suggested in #140765 (review)

Linked PRs

• gh-140806: add docs for enum.bin function #140807
• [3.14] gh-140806: add docs for enum.bin function (GH-140807) #143726
• [3.13] gh-140806: add docs for enum.bin function (#140807) #143740

[picnixz]

Oups, the 3.13 backport wasn't done yet.