Update link to Community Toolkit Contributing.md

Author: enitimeago

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 # Contributing to the Windows Community Toolkit Documentation
 
-Please visit the [contribution guidelines](https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/master/contributing.md) for the Windows Community Toolkit.
+Please visit the [contribution guidelines](https://github.com/CommunityToolkit/WindowsCommunityToolkit/blob/main/Contributing.md) for the Windows Community Toolkit.
 
 Documentation is **required** when adding, removing, or updating a control or an API in the Windows Community Toolkit. To update the documentation, you must submit a separate Pull Request in this repository as well (use the *master* branch for typos/improvements and *dev* for new features).