Fix command to check outgoing call to route migration

source/installation/xivo/upgrade/upgrade_from_borealis_to_callisto.rst

@@ -35,7 +35,7 @@ On XiVO PBX
 
   #. at the end of the upgrade check if there was any error during outcall migration to route::
 
-      xivo-dcomp logs -t db | grep '\[MIGRATE_OUTCALL\].*WARNING'
+      zgrep '\[MIGRATE_OUTCALL\].*WARNING' /var/log/postgresql/postgresql-11-main.log*
   #. if yes, follow our :ref:`migration guide <callisto_route_upgrade_guide>`.
 
 * Postgresql: postgresql service now runs inside a container. During upgrade the database was re-imported