README.md: Help and Discussion

README.md

@@ -18,6 +18,17 @@ native extension, but since RbNaCl is implemented with FFI, works on JRuby too!
 [libsodium]: https://github.com/jedisct1/libsodium
 [NaCl]: http://nacl.cr.yp.to/
 
+## Help and Discussion
+
+Have questions? Want to suggest a feature or change? Join a discussion group:
+
+* [Crypto.rb Gitter]: web-based chat about Ruby crypto projects including **rbnacl-libsodium**.
+* [Crypto.rb Google Group]: join via web or email ([crypto-rb+subscribe@googlegroups.com])
+
+[Crypto.rb Gitter]: https://gitter.im/crypto-rb/Lobby
+[Crypto.rb Google Group]: https://groups.google.com/forum/#!forum/crypto-rb
+[crypto-rb+subscribe@googlegroups.com]: mailto:crypto-rb+subscribe@googlegroups.com?subject=subscribe
+
 ## Installation
 
 Add this line to your application's Gemfile: