Don't use he in docs when its not needed

Author: dawehner

Extension/Core/Type/ChoiceType.php

@@ -396,7 +396,7 @@ private function addSubForm(FormBuilderInterface $builder, $name, ChoiceView $ch
         if ($options['multiple']) {
             $choiceType = __NAMESPACE__.'\CheckboxType';
             // The user can check 0 or more checkboxes. If required
-            // is true, he is required to check all of them.
+            // is true, they are required to check all of them.
             $choiceOpts['required'] = false;
         } else {
             $choiceType = __NAMESPACE__.'\RadioType';