Pull requests (PRs) are an interface to discuss proposed changes to be integrated into a project. As a sysadmin, you might typically hear about developers using PRs to manage code in a public repository. Even if you don’t know how to code, you can still contribute with PRs to your favorite project.
As a frequent user of r10k, but someone unfamiliar with ruby, I can’t contribute very much to the inner workings of the program. However, as a user, I’m in a good position to provide feedback on the user experience. To that end, I forked the repository on github and created some branches to update the documentation to (hopefully!) improve it for other users. Afterward, I submitted PRs and worked with Adrien Thebo, the project maintainer, to fine tune the PRs till they were correctly implemented. The results of that PR are here and the other PRs are merged or still being edited.
As I’ve noted before, documentation matters. If you can’t or aren’t willing to contribute code on a project, improving the documentation is a great way to give back to the community. Give it a shot!