They appear to support multiple languages but I've not tested yet.
What I'm going to do soon is add the gitbook project to a github repo which is automatically synced, and then I can add contributors to the github repo who can add translations. Then it should hopefully just work to have
and so on. And other volunteers / defold team members who are added to the git as admins can accept pull requests for text corrections / additions over time.
Please wait until I setup the github repo before doing translation so you can work from the raw files. I still have more setup work to do that I've not had time to do yet.