feat: document webapp boilerplate
This commit adds a first pass documentation of our new-style webapp boilerplate. I've tried to cover setup and configuration issues which were reported to me in dedicated how-to documents.
A full list of all poe tasks is included in a reference guide.
Finally a more discussive guide is added which covers the "how" and the "why" of the boilerplate.
I fully expect both the reference and how-to guides to need more content over time but I think this is minimally useful ATM.
Closes #210 (closed)