Add Gitter Chatroom to Readme (#681)

* Update README.md

* Use Markdown Anchor link instead of URL

README.md

@@ -24,6 +24,11 @@ source .travis/s2n_setup_env.sh
 .travis/s2n_travis_build.sh
 ```
 
+### Have a Question?
+If you have any questions about Submitting PR's, Opening Issues, s2n API usage, or something similar, we have a public chatroom available here to answer your questions: https://gitter.im/awslabs/s2n
+
+Otherwise, if you think you might have found a security impacting issue, please instead follow [our Security Notification Process.](#security-issue-notifications)
+
 ## Using s2n
 
 The s2n I/O APIs are designed to be intuitive to developers familiar with the widely-used POSIX I/O APIs, and s2n supports blocking, non-blocking, and full-duplex I/O. Additionally there are no locks or mutexes within s2n.