The documentation itself is written in ReStructuredText (RST) and its sources are available in another repository. It's result is a webpage that can be either found at the jamovi-webpage (this is the officical place, but not updated as frequently) or on ReadTheDocs (which is the testing ground with more frequent updates).
If you are willing to contribute to the project with translating it into your language, please obtain further information about how to get involved. The following status overview tells you how much content for your language already has been translated.
Please also have a look at two other translation projects related to jamovi, the translation of the jamovi user interface and the translation of the textbook "Learning statistics with jamovi"
We are grateful to the Weblate-team who host libre projects as ours free of charge.