Added a comment

inc/config.php

@@ -105,6 +105,7 @@
 	define('WIKI_MARKUP',	true, true);
 	// Whether to turn URLs into functional links
 	define('MARKUP_URLS',	true, true);
+	// Complex regular expression to catch URLs
 	define('URL_REGEX',		'/' .	'(https?|ftp):\/\/' .	'([\w\-]+\.)+[a-zA-Z]{2,6}' .	'(\/([\w\-~\.#\/?=&;:+%]+))?' . '/', true);
 
 	// Allowed file extensions