update contributing guidelines

Author: tiagoschenkel

CONTRIBUTING.md

@@ -25,17 +25,22 @@ $ yarn test
 ## Guidelines
 
 - Please try to [combine multiple commits before
-pushing](http://stackoverflow.com/questions/6934752/combining-multiple-commits-before-pushing-in-git)
+pushing](http://stackoverflow.com/questions/6934752/combining-multiple-commits-before-pushing-in-git).
 
 - Please use `TDD` when fixing bugs. This means that you should write a unit
 test that fails because it reproduces the issue, then fix the issue and finally run
 the test to ensure that the issue has been resolved. This helps us to prevent
 fixed bugs from happening again in the future.
+
 - Always format your code using `yarn run autoformat`.
+
 - Please keep the test coverage at 100%. Write additional unit test if
-necessary
+necessary.
+
 -  Please create an issue before sending a PR if your commit is going to change the
-public interface of SignalsJS or it includes significant architecture
+public interface of the package or it includes significant architecture
 changes.
+
 - Feel free to ask for help from other members of the RobotlegsJS team via the
-chat or github issues.
+[gitter chat](https://gitter.im/RobotlegsJS/RobotlegsJS) or
+[github issues](https://github.com/RobotlegsJS/SignalsJS/issues).