[ci skip] Fix a docblock
diff --git a/system/database/DB_cache.php b/system/database/DB_cache.php
index 671147b..d07c755 100644
--- a/system/database/DB_cache.php
+++ b/system/database/DB_cache.php
@@ -40,7 +40,7 @@
 	/**
 	 * Constructor
 	 *
-	 * @param	&$db
+	 * @param	object	&$db
 	 * @return	void
 	 */
 	public function __construct(&$db)