CONTRIBUTING.MD not existing in repo

Under Getting Involved section when clicking on [How to Contribute](https://github.com/h5bp/Front-end-Developer-Interview-Questions/blob/master/.github/CONTRIBUTING.md) the file is not there. That is because it is pointing to `master` branch instead of `main`

<img width="923" height="266" alt="Image" src="https://github.com/user-attachments/assets/0ceb96dc-514b-4d7e-a5c0-8bd737a78aee" />