carrierroute: docs - note about config file ownership

- GH #2369

(cherry picked from commit 214c762c46d5cd5892d2ddc06a25193a01164e8b)
(cherry picked from commit 35d977aed4c7137d34d4cf8216d503ac48f1e423)

src/modules/carrierroute/doc/carrierroute_admin.xml

@@ -206,7 +206,8 @@ modparam("carrierroute", "config_source", "file")
     <section>
 	    <title><varname>config_file</varname> (string)</title>
 	    <para>
-		    Specifies the path to the config file.
+			Specifies the path to the config file. The file has to be owned by
+			the user and group used to run &kamailio;.
 	    </para>
 	    <para>
 		    <emphasis>