docs(dev-guide): review on how to set commit message

Author: KaiSchwarz-cnic

docs/developmentguide.rst

@@ -60,8 +60,10 @@ Pull Request (PR) Procedure
 * fork our project and create a new branch.
 * clone it and check this branch out
 * apply your desired changes / extensions
-* commit and push it to remote
-* open a pull request (PR)
+* commit and push it to remote. Please follow these format rules_.
+  We suggest to use commitizen_.
+* open a pull request (PR) - check results of Travis CI.
+  There are possibly Code issues you can correct.
 
 **We care then about the rest** - no need to worry about things like
 building current realease and versioning.
@@ -73,6 +75,9 @@ TIA for your PR and thus for your support of this project. As we have
 further SDKs in other languages, it might take a bit of time to check
 if we can role out that PR as we want to keep all our SDKs aligned.
 
+.. _rules: https://github.com/angular/angular.js/blob/master/DEVELOPERS.md#-git-commit-guidelines)
+.. _commitizen:  https://github.com/commitizen/cz-cli/blob/master/README.md
+
 Versioning
 ----------