[3.13] gh-149574: Document that is_typeddict, is_protocol, is_dataclass, isclass return False for generic aliases (GH-149604) (#149752)

gh-149574: Document that is_typeddict, is_protocol, is_dataclass, isclass return False for generic aliases (GH-149604)
(cherry picked from commit a4e51c8dac9fdd49ae26ff8c6cd3c808fd8ba15e)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>