Update support documentation to be more accurate

We were missing instructions to report security vulnerabilities,
and all of the documentation referred to Kenneth as the only
source of support. We were also missing a link to StackOverflow.

docs/community/support.rst

@@ -5,12 +5,27 @@ Support
 
 If you have questions or issues about Requests, there are several options:
 
+StackOverflow
+-------------
+
+If your question does not contain sensitive (possibly proprietary)
+information or can be properly anonymized, please ask a question on
+`StackOverflow <https://stackoverflow.com/questions/tagged/python-requests>`_
+and use the tag ``python-requests``.
+
 Send a Tweet
 ------------
 
 If your question is less than 140 characters, feel free to send a tweet to
-`@kennethreitz <http://twitter.com/kennethreitz>`_.
+`@kennethreitz <https://twitter.com/kennethreitz>`_ or
+`@sigmavirus24 <https://twitter.com/sigmavirus24>`_.
 
+Vulnerability Disclosure
+------------------------
+
+If you think you have found a potential security vulnerability in requests,
+please email `sigmavirus24 <mailto:graffatcolmingov@gmail.com>`_ and
+`Lukasa <mailto:cory@lukasa.co.uk>`_ directly. **Do not file a public issue.**
 
 File an Issue
 -------------
@@ -34,4 +49,9 @@ IRC
 The official Freenode channel for Requests is
 `#python-requests <irc://irc.freenode.net/python-requests>`_
 
-I'm also available as **kennethreitz** on Freenode.
+The core developers of requests are on IRC throughout the day.
+You can find them in ``#python-requests`` as:
+
+- kennethreitz
+- lukasa
+- sigmavirus24