[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

if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
           ask_confirm=False):
    rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
        ask_confirm=False)