bpo-44392: Add Py_GenericAlias to C API docs (GH-26724)


Also fix stable ABI type definitions
(cherry picked from commit 6773c3eaa735b5061b4a97f2c730703a32d8c9ff)

Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
6 files changed