The source files for all the ROS2 documentation are under the /source directory. The sources are in ReStructuredText format (.rst).
Please refer to the README.md file in this repository for instructions on how to build the documentation locally.
If you are a Github user, the most effective way to contribute is to submit a pull request with the changes you want to suggest.
If you don't feel comfortable creating a pull request or you want to make a general suggestion or start a discussion about the documentation, you can create a Github issue on this repository.
To contribute to the ROS2 source code project please refer to the ROS2 contributing guidelines.