Arise, oh the Documentation!
UNA Documentation comes in a few different forms, for different purposes. We are still at the early (still BETA) days, and a lot of functionality is changing, so the documentation is rather raw as well. Still, there are a few really helpful articles available and more is on the way.
Most of the UNA-platform docs are at the UNA Github Repo. Anything specific to UNA.io services, however, is at the UNA.io Articles section (powered by Articles UNA App from AQB Soft).
Here is the current index for the UNA platform docs (some are still "in progress"):