Update form.rst for flattened form errors

Updated to reflect the code.

Author: DocFX

components/form.rst

@@ -750,7 +750,7 @@ method to access the list of errors. It returns a
     $errors = $form['firstName']->getErrors();
 
     // a FormErrorIterator instance in a flattened structure
-    $errors = $form->getErrors(true);
+    $errors = $form->getErrors(false, true);
 
     // a FormErrorIterator instance representing the form tree structure
     $errors = $form->getErrors(true, false);