[3.12] gh-73580: Docs for tunnelling TLS through TLS (GH-22539) (GH-1…

…16149)

(cherry picked from commit 91c3c64)

Co-authored-by: Carl Bordum Hansen <carl@bordum.dk>

Doc/library/ssl.rst

@@ -1765,6 +1765,9 @@ to speed up repeated connections from the same clients.
 
    *session*, see :attr:`~SSLSocket.session`.
 
+   To wrap an :class:`SSLSocket` in another :class:`SSLSocket`, use
+   :meth:`SSLContext.wrap_bio`.
+
    .. versionchanged:: 3.5
       Always allow a server_hostname to be passed, even if OpenSSL does not
       have SNI.