GitHub provides a wonderful avenue for technical writers, in addition to developers. I have used GitHub internally with my company for quite a while, and it lets me track my project for any documentation issues. I like going through the email updates to see what has changed which could affect the documentation. Our documentation is sourced in a separate CMS, but I understand the GitHub workflow perfectly. Recently, I decided that I want to also utilize my skills to help projects in the public realm. I will start posting projects and various musings that you can view on my GitHub profile. I will also start contributing to open source documentation for various projects.
Feel free to reach out to me if you need help with improving your documentation on GitHub!
Additionally, I have also started completing challenges from freeCodeCamp to showcase my HTML and CSS skills. I have a busy Fall planned with work and I am also attending LavaCon in New Orleans next month, and I will update my GitHub repositories as I find time. I feel that it will help web developers and technical writers, just like various projects have helped me improve my skills.