fix typo in comments
diff --git a/system/database/DB_forge.php b/system/database/DB_forge.php
index c8d773c..f6ee2a6 100644
--- a/system/database/DB_forge.php
+++ b/system/database/DB_forge.php
@@ -828,7 +828,7 @@
 	 */
 	protected function _attr_type(&$attributes)
 	{
-		// Usually overriden by drivers
+		// Usually overridden by drivers
 	}
 
 	// --------------------------------------------------------------------