[3.12] gh-122519: Adding socket module shutdown() constants description (GH-122543) (#123094)

gh-122519: Adding socket module shutdown() constants description (GH-122543)
(cherry picked from commit 8a59deca59aa9452e71bb49e909199fbb41a5de7)

Co-authored-by: Damien <81557462+Damien-Chen@users.noreply.github.com>