May I kindly remind you there is also joplin-docs which aims to offer a better documentation center. The website is up and running. Why not give a try ? Anyone can add/edit content or create/suggest a new structure 
First step is to define the new doc structure we want as Laurent remind us several times (the topic Refactor project documentation may be the appropriate place for this)
However I don't see why not start gathering the doc. IMHO the temporary structure we put in place (whatever it is.) will be more effective and user-friendly than actual solution And even if this is not the final solution at least we start building a better doc center.
The point is to have the doc in md format, editable by the community. This to have one reference point once for all. For me docs and website can live separably. That's good to keep flexibility and allow those 2 projects to evolve easily.