topos: note in docs that masking callid is not implemented yet

modules/topos/doc/topos_admin.xml

@@ -89,6 +89,11 @@ modparam("topos", "db_url", "&exampledb;")
 	</section>
 	<section id="topos.p.mask_callid">
 		<title><varname>mask_callid</varname> (int)</title>
+		<para>
+			Note: this functionality is not implemented yet - the
+			parameter is present in order to be in pair with topoh
+			module.
+		</para>
 		<para>
 			Whether to replace or not the Call-ID with another
 			unique id generated by &kamailio;.