UX: improve FilterOrder box design

src/Bundle/ChillMainBundle/Form/Type/Listing/FilterOrderType.php

@@ -38,6 +38,9 @@ final class FilterOrderType extends \Symfony\Component\Form\AbstractType
             $builder->add('q', SearchType::class, [
                 'label' => false,
                 'required' => false,
+                'attr' => [
+                    'placeholder' => 'activity_filter.Search',
+                ]
             ]);
         }