[3.12] gh-122511: Improve documentation for object identity of mutable/immutable types (GH-122512) (#122779)

gh-122511: Improve documentation for object identity of mutable/immutable types (GH-122512)
(cherry picked from commit 76bdeebef6c6206f3e0af1e42cbfc75c51fbb8ca)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>