Add communication channels in a CONTRIBUTING.md.

CONTRIBUTING.md

@@ -0,0 +1,9 @@
+# How to contribute
+
+Contributors communicate through various channels:
+
+- GitHub: [miguelfreitas/twister-core](https://github.com/miguelfreitas/twister-core/issues/)
+- Google Groups: [`twister-users`](http://groups.google.com/d/forum/twister-users)
+- IRC: [`#twister`](https://kiwiirc.com/client/chat.freenode.net/#twister)
+- Wiki: http://wiki.twister.net.co
+- Twitter: [@TwisterPtoP](https://twitter.com/TwisterPtoP)

README.md

@@ -184,3 +184,7 @@ But be careful, it is in beta stage.
 
     cd ~/.twister/
     git clone https://github.com/iHedgehog/twister-calm.git ./html
+
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md)