Thank you for your interest in contributing. Getting started is fairly simple.
Fork this repository, clone your fork to your local machine, work on your contribution in a branch, and when ready, open a Pull Request with us.
You can always open a GitHub Issue on this repository. There you can let us know what needs a fix, a doc we don't have that you would like to see, or leave feedback.
The bottom of every doc at https://circleci.com/docs/ also have convenient links to get you started in editing a doc or adding an issue.