Some thoughts on how the final product will look and work.
The layout and design ideas demonstrated here are a first cut. Assistance from more design oriented contributors would be very welcome.
The Manual will be easier to use by virtue of extensive use of Categories. I am sure that there are folk who have experience of Joomla categorisation. I would value a pointer to previous examples.
One triad of Categories will be Beginner Intermediate Expert. Any Topic page will belong to at least one and it could belong to more than one. The idea is to allow readers to follow paths through the Manual suitable for their skill level.