add more info

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@9706 d0543943-73ff-0310-b7d9-9358b9ac24b2

conf/dialplan/default.xml

@@ -10,6 +10,11 @@
       </condition>
     </extension>
     
+    <!--
+	Try to get the domain from the sip_auth_realm otherwise it will
+	default domain in vars.xml for cases it can't figure it out.
+
+    -->
     <extension name="set_domain" continue="true">
       <condition field="${target_domain}" expression="^$" break="never"/>
       <condition field="source" expression="mod_sofia" break="never">