docs: update stale link (#684)

Author: SzaszkowMaksim

.changeset/warm-badgers-thank.md

@@ -0,0 +1,5 @@
+---
+'rock-docs': patch
+---
+
+docs: update stale link

CONTRIBUTING.md

@@ -4,7 +4,7 @@
 
 All work on Rock happens directly on GitHub. Contributors send pull requests which go through review process.
 
-> **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).
 
 1. Fork the repo and create your branch from `main` (a guide on [how to fork a repository](https://help.github.com/articles/fork-a-repo/)).
 1. Run `pnpm i` to install all required dependencies.