In this project, I'm working through the material in the new text by Gelman, Hill, and Vehtari, Regression and other stories. You can find the official code from Vehtari at https://github.com/avehtari/ROS-Examples/. I'm really not looking for contributions, at this time. However, if you find gross errors or have concerns, feel free to open a GitHub issue.
For each chapter, you can find the raw code in the .Rmd files. The .md files contain versions of the chapters rendered into HTML using the github_document format, which is probably what casual users will be looking for. To my knowledge, there still isn’t a good way to render LaTeX on GitHub, but the .md files do an okay job, otherwise.