modules_k/nathelper: improved handle_ruri_alias() documentation

- Improved handle_ruri_alias() documentation based on suggestion by Klaus.

modules_k/nathelper/README

@@ -848,7 +848,13 @@ start_recording();
 6.15.  handle_ruri_alias()
 
    Checks if Request URI has alias param and if so, removes it and sets
-   $du based on its value.
+   $du based on its value. Note that this means that routing of request is
+   based on alias parameter value of Request URI rather than Request URI
+   itself. If you call handle_ruri_alias() on a request, make thus sure
+   that you screen alias parameter value of Request URI the same way as
+   you would screen Request URI itself.
+
+   Note that th
 
    This function can be used from REQUEST_ROUTE, BRANCH_ROUTE, and
    LOCAL_ROUTE.

modules_k/nathelper/doc/nathelper_admin.xml

@@ -1031,7 +1031,16 @@ start_recording();
 		</title>
 		<para>
 		Checks if Request URI has alias param and if so, removes
-		it and sets $du based on its value.
+		it and sets $du based on its value.  Note that this
+		means that routing of request is based on alias
+		parameter value of Request URI rather than Request URI
+		itself. If you call handle_ruri_alias() on a request,
+		make thus sure that you screen alias parameter value of
+		Request URI the same way as you would screen
+		Request URI itself.
+		</para>
+		<para>
+		Note that th		
 		</para>
 		<para>
 		This function can be used from