qapi-schema: Rocker doc section contains unrelated stuff, fix

Bug: section "Rocker switch device" starts with the rocker stuff, but
then has unrelated stuff, like ReplayMode, xen-load-devices-state, ...

Cause: rocker.json is included in the middle of section "QMP commands".

Fix: include it in a sane place, namely next to the other sub-schemas.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1503602048-12268-4-git-send-email-armbru@redhat.com>
