This site is hosted on the GitBook platform, which lets users update the documentation, like in a Wiki. Making changes is super easy because it's done directly in the internet browser, nothing to install.
If you want to make some changes just send me an email (here) I'll reply with a link to grant you write access rights to the JJazzLab GitBook.
If you're a GitHub user you can also use the Edit on GitHub button in the upper right of each page, or make a pull-request directly on the JJazzLab-X-UserGuide repository.
Translate the online doc
You can also help by fixing or adding new translations. Currently there is 2 languages, English and Japanese. If you language does not exist yet, contact me (here) so that I add a "GitBook variant" for that language.