Your contributions are absolutely welcome! Here are two ways you can help:
If you know your way around Git and Github, you can fork this repo, commit your changes, then open a pull request to have your changes reviewed and integrated directly into this repo. Here is a good guide on how to do that.
If Git isn't your thing, that's also totally fine! Just open up a new Issue describing the changes you'd like to see. Post any relevant links, images, descriptions, potential topics, or anything else you think would be a good fit for the document. When I see your issue I'll integrate the changes myself and let you know ASAP!