[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 8a59dec)

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

Author: miss-islington

Doc/library/socket.rst

@@ -695,6 +695,13 @@ Constants
 
    .. versionadded:: 3.12
 
+.. data:: SHUT_RD
+          SHUT_WR
+          SHUT_RDWR
+
+   These constants are used by the :meth:`~socket.socket.shutdown` method of socket objects.
+
+   .. availability:: not WASI.
 
 Functions
 ^^^^^^^^^