textopsx: documented return behavior of msg_apply_changes()

modules/textopsx/README

@@ -119,6 +119,13 @@ Chapter 1. Admin Guide
    the SIP message buffer so far, using this function might change the
    behaviour of your config. Do test your config properly!
 
+   The function returns true (1) on success. If it is failure before the
+   new content is build, the function returns false (-1), the old content
+   is still in place. If parsing of the new content is failing, the
+   function stops executions of the config file (the internal structure is
+   no longer valid for config processing, like it happens when a broken
+   message is received from network).
+
    This function can be used from REQUEST_ROUTE or ONREPLY_ROUTE.
 
    Example 1.1. msg_apply_changes() usage

modules/textopsx/doc/functions.xml

@@ -16,6 +16,14 @@
 		the behaviour of your config.  Do test your config properly!
 		</para>
    		<para>
+		The function returns true (1) on success. If it is failure before the
+		new content is build, the function returns false (-1), the old content
+		is still in place. If parsing of the new content is failing, the
+		function stops executions of the config file (the internal structure
+		is no longer valid for config processing, like it happens when a
+		broken message is received from network).
+		</para>
+		<para>
 		This function can be used from REQUEST_ROUTE or ONREPLY_ROUTE.
 		</para>
 		<example>