[doc] Update cubicweb-ctl page about how to run an instance
* remove mention of start/stop/restart/status commands that do not exist anymore
* briefly mention the "pyramid" and point to respective documentation page
* mention that a WSGI server should be used in production
from yams.buildobjs import RelationDefinition
class ARelation(RelationDefinition):
subject = 'CWUser'
object = 'CWGroup'