bpo-39616: clarify SSLContext.check_hostname effect (GH-18484)

It doesn't actually affect whether match_hostname() is called (it
never is in this context any longer), but whether hostname
verification occurs in the first place.
(cherry picked from commit 9798cef)

Co-authored-by: Ville Skyttä <[email protected]>

Author: miss-islington

Doc/library/ssl.rst

@@ -1878,7 +1878,7 @@ to speed up repeated connections from the same clients.
 
 .. attribute:: SSLContext.check_hostname
 
-   Whether to match the peer cert's hostname with :func:`match_hostname` in
+   Whether to match the peer cert's hostname in
    :meth:`SSLSocket.do_handshake`. The context's
    :attr:`~SSLContext.verify_mode` must be set to :data:`CERT_OPTIONAL` or
    :data:`CERT_REQUIRED`, and you must pass *server_hostname* to