fix: docs (#2838)

Author: honkinglin

CONTRIBUTING.md

@@ -13,7 +13,7 @@ We welcome any type of contribution, not only code. You can help with
 
 ## Your First Contribution
 
-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).
+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/courses/how-to-contribute-to-an-open-source-project-on-github).
 
 ## Submitting code