There are two changes here:
1. Removes the mention of the message queue since the cell0
mapping has a transport_url but it's effectively none meaning
we don't use RPC for accessing cell0 objects.
2. Adds boilerplate wording on the config option used to determine
the database connection if the --database_connection argument
is not specified. This was particularly confusing at one point
because it originally started out as the CONF.api_database.connection
but we changed that mid-cycle in Ocata since the schema for cell0
is the cell (nova) DB, not the nova_api DB.
Change-Id: Ie869f8565460600da767d99e9e397abc5e8bf0e0
Matt Riedemann
9ca2a51ec4