Moves muc definition to be last.

Fixes common problem where people following https://github.com/jitsi/jicofo#secure-domain have a syntax error, forgetting the comma after muc definition.

config.js

         // XMPP domain.
         domain: 'jitsi-meet.example.com',
 
-        // XMPP MUC domain. FIXME: use XEP-0030 to discover it.
-        muc: 'conference.jitsi-meet.example.com'
-
         // When using authentication, domain for guest users.
         // anonymousdomain: 'guest.example.com',
 
 
         // Focus component domain. Defaults to focus.<domain>.
         // focus: 'focus.jitsi-meet.example.com',
+
+        // XMPP MUC domain. FIXME: use XEP-0030 to discover it.
+        muc: 'conference.jitsi-meet.example.com'
     },
 
     // BOSH URL. FIXME: use XEP-0156 to discover it.