[2.7] bpo-21649: Add RFC 7525 and Mozilla server side TLS (GH-3387) (GH-3400)

Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit ad0ffa033ea79f7c7cb14b1b1cc10888ea9e9913)
diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst
index 183c17b..36beb17 100644
--- a/Doc/library/ssl.rst
+++ b/Doc/library/ssl.rst
@@ -1810,3 +1810,9 @@
 
    `IANA TLS: Transport Layer Security (TLS) Parameters <https://www.iana.org/assignments/tls-parameters/tls-parameters.xml>`_
        IANA
+
+   `RFC 7525: Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) <https://tools.ietf.org/html/rfc7525>`_
+       IETF
+
+   `Mozilla's Server Side TLS recommendations <https://wiki.mozilla.org/Security/Server_Side_TLS>`_
+       Mozilla