etc/kamailio.org: do record route for REFER

- it creates a subscription dialog
- https://datatracker.ietf.org/doc/html/rfc3515#section-2

etc/kamailio.cfg

@@ -578,7 +578,7 @@ request_route {
 	# record routing for dialog forming requests (in case they are routed)
 	# - remove preloaded route headers
 	remove_hf("Route");
-	if (is_method("INVITE|SUBSCRIBE")) {
+	if (is_method("INVITE|SUBSCRIBE|REFER")) {
 		record_route();
 	}
 
@@ -700,8 +700,8 @@ route[WITHINDLG] {
 		} else if ( is_method("ACK") ) {
 			# ACK is forwarded statelessly
 			route(NATMANAGE);
-		} else if ( is_method("NOTIFY") ) {
-			# Add Record-Route for in-dialog NOTIFY as per RFC 6665.
+		} else if ( is_method("NOTIFY|REFER") ) {
+			# Add Record-Route for in-dialog NOTIFY and REFER (RFC6665, RFC3515)
 			record_route();
 		}
 		route(RELAY);