Improve documentation for `__mro_entries__`

[AlexWaygood]

Documentation

The __mro_entries__ method is documented in the data model here: https://docs.python.org/3.11/reference/datamodel.html#resolving-mro-entries.

However, it's not currently possible to reference it using the expected syntax (~object.__mro_entries__) in other parts of the documentation.

Linked PRs

• gh-103373: Improve documentation for __mro_entries__ #103374
• [3.11] gh-103373: Improve documentation for __mro_entries__ (GH-103374) #103376
• gh-103373: __mro_entries__ docs: improve cross references #103398
• [3.11] gh-103373: __mro_entries__ docs: improve cross references (GH-103398) #103440