Creating a composite action - GitHub Docs
In this guide, you'll learn about the basic components needed to create and use a packaged composite action. To focus this guide on the components needed to package the action, the functionality of the action's code is minimal. The action prints "Hello World" and then "Goodbye", or if you provide a custom name, it prints "Hello [who-to-greet]" and then "Goodbye".
https://docs.github.com/en/actions/creating-actions/creating-a-composite-action#creating-an-action-metadata-file
