docs: Add references to AsyncMock in unittest.mock.patch (GH-13681)


Update the docs as patch can now return an AsyncMock if the patched
object is an async function.
(cherry picked from commit f5e7f39d2916ed150e80381faed125f405a11e11)

Co-authored-by: Mario Corchero <mcorcherojim@bloomberg.net>
2 files changed