updating a readme dead link (#39133)

Author: MetzinAround

README.md

@@ -148,7 +148,7 @@ Gatsby is dedicated to building a welcoming, diverse, safe community. We expect
 
 Whether you're helping us fix bugs, improve the docs, or spread the word, we'd love to have you as part of the Gatsby community!
 
-Check out our [**Contributing Guide**](https://www.gatsbyjs.com/contributing/how-to-contribute/) for ideas on contributing and setup steps for getting our repositories up and running on your local machine.
+Check out our [**Contributing Guide**](https://www.gatsbyjs.com/contributing/) for ideas on contributing and setup steps for getting our repositories up and running on your local machine.
 
 ### A note on how this repository is organized