We have a Cylc 8 version of the User Guide, which we will make available with the upcoming 8.0a2 alpha release. It does document some changes and improvements to the workflow configuration syntax, but a) there are actually not many of those as we are trying to maintain backward compatibility in that respect; and b) it does not yet document the Cylc 8 architecture, how to use it, or any of the implications thereof - which is where the really big Cylc 8 changes are.
We definitely do not recommend using Cylc 8 for anything important yet, it is still undergoing heavy development and many important issues have not been addressed at this stage. Hopefully you have seen the warnings here: https://github.com/cylc/cylc-conda/blob/master/README.md#current-limitations
However, if you want (or need) to keep experimenting, feel free to keep asking questions here.
Note that cylc-8.0a1 was a very early release. We intend to release cylc-8.0a2 by end of January - or soon thereafter - with some major improvements. Or you can start at the bleeding edge, with git clones of all the Cylc 8 components.
The Cylc 8 User Guide, BTW, is maintained in its own repository, here: https://github.com/cylc/cylc-doc