[ticket/12715] Cleanup comments in \phpbb\cache\driver\*

PHPBB3-12715

phpBB/phpbb/cache/driver/file.php

@@ -28,6 +28,8 @@ class file extends \phpbb\cache\driver\base
 
 	/**
 	* Set cache path
+	*
+	* @param string $cache_dir Define the path to the cache directory (default: $phpbb_root_path . 'cache/')
 	*/
 	function __construct($cache_dir = null)
 	{