fix broken link to egghead.io

Author: mnusurov

contributing.md

@@ -30,8 +30,8 @@ Thank you for your contributions to making this list a valuable resource for the
 ---
 
 **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)
+[How to Contribute to an Open Source Project on GitHub](https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github)
 
 **Updating your PR**
 A lot of times, making a PR adhere to the standards above can be difficult.
-If the maintainers notice anything that we'd like changed, we'll ask you to edit your PR before we merge it. There's no need to open a new PR, just edit the existing one. If you're not sure how to do that, [here is a guide](https://github.com/RichardLitt/knowledge/blob/master/github/amending-a-commit-guide.md) on the different ways you can update your PR so that we can merge it.
+If the maintainers notice anything that we'd like changed, we'll ask you to edit your PR before we merge it. There's no need to open a new PR, just edit the existing one. If you're not sure how to do that, [here is a guide](https://github.com/RichardLitt/knowledge/blob/master/github/amending-a-commit-guide.md) on the different ways you can update your PR so that we can merge it.