Updating CONTRIBUTING.md

Author: deeg

CONTRIBUTING.md

@@ -32,4 +32,5 @@ We are always looking for the quality contributions and will be happy to accept
 * Please assure that you are submitting quality code, specifically make sure that:
   * You have accompanying tests and all the tests are passing.
   * Your PR doesn't break the build; check the Travis-CI build status after opening a PR and push corrective commits if anything goes wrong
-  * You are using 2 space indentation
+  * You are using 2 space indentation
+  * Your commits conform to the conventions established [here](https://github.com/ajoslin/conventional-changelog/blob/master/conventions/angular.md)