If you need to contact us, just send a letter to firstname.lastname@example.org.
You can file any issues you encounter with any of our manuals from their respective issue trackers on GitHub. Just go to the project page for the radio model you'd wish to report an issue for and click on "Issues" in the top nav-bar.
Of course, if you don't feel like signing up for a GitHub account you can just mail us about it. It should however be noted that issues filed on GitHub are there for everyone to read, meaning we won't be able to slack off on you.
So you want to contribute? Great! Welcome aboard! Feel free to clone the repository of any project you'd like to contribute to. Make sure that you carefully read the
CONTRIBUTIONS file before you start working or commit anything.