FormAction.php: enhance doc

extension/qfq/qfq/form/FormAction.php

@@ -591,7 +591,7 @@ class FormAction {
         foreach ($columns as $col) {
 
             $key = $col[COLUMN_FIELD];
-            // Only copy values which exist on source AND destination.
+            // Only copy columns which exist on source AND destination.
             if (!isset($row[$key])) {
                 continue;
             }