GitHub Actions documentation https://docs.github.com/en/actions
Basic terms https://docs.github.com/en/actions/about-github-actions/understanding-github-actions
Workflow syntax https://docs.github.com/en/actions/writing-workflows/workflow-syntax-for-github-actions
Free plan limitations https://docs.github.com/en/get-started/learning-about-github/githubs-plans#github-free-for-personal-accounts