Pulling up documentation cluster from under source

* The documentation cluster is not rightfully held under source as it is
not source code--it is documentation.
* The documentation cluster is now at the library root where it belongs.
* References have been provided in the appropriate places to ensure the
DOC_* classes are in-system and Clickable-view enabled per
documentation.

NOTE: From here, we can revamp the documentation prose to take advantage
of the in-system status in Clickable-view to create note-entry PND
references.