* Add deprecation warning to old integration
* Add user docs
* Add admin docs

- Move steps to new doc
- Move all concepts to different docs

Many code blocks are 4spaced, and they render in GitLab
without coloring as a result, even though they are
fenced with a language label. If in a list, other items
will render as being in a code block too, even if not
meant to. This fixes all these issues for many admin
docs (part 2)

Markdown renderers find it easier to determine
where lists start and end when lists are surrounded
by new lines.

For consistency, also ensure entries in the list
are aligned when they span multipls lines.