Has the documentation of the various components of LO 5.x ceased?
No! In particular, there’s an active effort to update the user guides, starting with the Getting Started Guide, which the Documentation Team is working to update for version 6.0 in time for its release in early 2018. You can find these discussions in the documentation mailing list and info on the documentation development process on the wiki.
There is work going on with the in-program help as well, improving the infrastructure to make it easier to edit and view the content (if I understand it correctly – I’m not that well-informed on this).
Quoting @khanson679: “…version 6.0 in time for its release in early 2017.”