add docs for force-subscription-expires

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10768 d0543943-73ff-0310-b7d9-9358b9ac24b2

conf/sip_profiles/internal.xml

@@ -148,6 +148,8 @@
     <!--<param name="force-register-domain" value="$${domain}"/>-->
     <!--all inbound reg will stored in the db using this domain -->
     <!--<param name="force-register-db-domain" value="$${domain}"/>-->
+    <!--force suscription expires to a lower value than requested-->
+    <!--<param name="force-subscription-expires" value="60"/>-->
     <!-- disable register and transfer which may be undesirable in a public switch -->
     <!--<param name="disable-transfer" value="true"/>-->
     <!--<param name="disable-register" value="true"/>-->