jibri: set base URL for joining meetings

This will make Jibri join PUBLIC_URL/meetingName instead of https://meet.jitsi/meetingName.

jibri/rootfs/defaults/config.json

@@ -15,6 +15,8 @@
                 "{{ .Env.XMPP_SERVER }}"
             ],
             "xmpp_domain": "{{ .Env.XMPP_DOMAIN }}",
+            // An (optional) base url the Jibri will join if it is set
+            "baseUrl": "{{ .Env.PUBLIC_URL }}",
             // Jibri will login to the xmpp server as a privileged user 
             "control_login": {
                 "domain": "{{ .Env.XMPP_AUTH_DOMAIN }}",
@@ -28,7 +30,7 @@
             "control_muc": {
                 "domain": "{{ .Env.XMPP_INTERNAL_MUC_DOMAIN }}",
                 "room_name": "{{ .Env.JIBRI_BREWERY_MUC }}",
-		// MUST be unic for every instanse
+                // MUST be unic for every instanse
                 "nickname": "jibri-instanse-{{ .Env.JIBRI_INSTANCE_ID }}"
             },
             // All participants in a call join a muc so they can exchange