[3.14] gh-141388: Improve docs/tests for non-function callables as annotate functions (GH-142327) (#149304)

gh-141388: Improve docs/tests for non-function callables as annotate functions (GH-142327)
(cherry picked from commit c1940bcfc8a80d0d66f3f7f03e776d0d23ebb59b)

Co-authored-by: dr-carlos <77367421+dr-carlos@users.noreply.github.com>