Hey, it’s really great you want to contribute to the new default theme for the WordPress 4.4 release! Before you dive right in, we have a few pointers on how to contribute whilst it’s on Github.
The theme is synced regularly to the WordPress.org theme directory. Whatever you add, make sure you keep to the theme review handbook.
Here are some good ideas for commit messages:
All changes happen through a pull request made by contributors, ideally associated with an issue. After you send your proposed changes, one of the committers will review and test. After that we can merge them in.
When you add a pull request, please also update the CONTRIBUTORS.md with your WordPress.org username. This is a running list of all contributors and essential to give everyone that has helped make this project props when we finally merge into core.