Add missing relation types items in schema global variables
Some of these global variables are used, in particular, to control schema
views (web/views/schema.py).
While they are currently not properly documented (see #3360868), their
definition are currently incomplete (e.g. one could reasonably expect to find
``cw_schema`` in ``SYSTEM_RTYPES``).
Closes #3486114.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html