Update CONTRIBUTING.md

Author: lauthieb

CONTRIBUTING.md

@@ -15,6 +15,8 @@ Please note we have a code of conduct, please follow it in all your interactions
    Pull Request would represent. The versioning scheme we use is [SemVer](http://semver.org/).
 4. You may merge the Pull Request in once you have the sign-off of two other developers, or if you 
    do not have permission to do that, you may request the second reviewer to merge it for you.
+   
+**Working on your first Pull Request?** You can learn how from this *free* series [How to Contribute to an Open Source Project on GitHub](https://egghead.io/series/how-to-contribute-to-an-open-source-project-on-github)
 
 ## Code of Conduct