We welcome any contribution in the forms of feedback on social media, helping out on stackoverflow, whatever you can do helps. This page however focuses on how to contribute either documentation or source code. All of it is contained in the same git repository.
You will have to either know git already or learn it. You will love it! Minor documentation or spelling fixes can be performed directly in the github user interface. Anything beyond that needs a local repository and more.
Once to know how to use git you
fork the repository to your own github account
create a branch for your specific work (separate issues or changes should be separate branches)
verify it all builds and looks right (see the 'Developing' documentation for more on that)
send a pull request
the core committers will review the pull request
any suggested changes need to be done on the same branch and pushed to your repository, this will update the pull request
ideally two core committers agree and will pull in the change
the changelog then gets updated and you are done
delete your branch and pull in from upstream master
rinse and repeat …
All documentation is written in asciidoc and should be located in src/site/asciidoc. Navigation and other layout and design resources can be found in src/site and specifically src/site/site.xml. The documentation is published with each release and is available on GitHub. You can edit documentation in the github interface or in your local clone. Check out the documentation on developing for further tips and tricks.
A contribution can be anything useful to the project. It might be fixing an issue or enhancing the plugin somehow. Even a javadoc spelling fix is not too small to submit! The only thing you need to check is that you can build the plugin, because we enforce things like code style and so on automatically. However if you create a pull request, this is done automatically as part of our continuous integration setup. Check out the documentation on developing for further tips and tricks.