Guide created
The site exists. The map on the home page is a suggested starting outline of what learning to make music in REAPER involves; every topic on it is marked planned because nothing has been written up yet.
From here the guide grows out of questions: each REAPER question that gets answered is folded into a topic note (with a few "check yourself" questions for review), and a line is added here saying what changed. Topics move from planned to learning as notes appear, and to solid once they feel comfortable.