Add array example on ChoiceType choice_attr option

Author: LucileDT

reference/forms/types/options/choice_attr.rst.inc

@@ -13,6 +13,24 @@ If an array, the keys of the ``choices`` array must be used as keys::
     use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
     // ...
 
+    $builder->add('attending', ChoiceType::class, [
+        'choices' => [
+            1 => Apple,
+            2 => Banana,
+            3 => Durian,
+        ],
+        'choice_attr' => [
+            1 => ['data-color' => 'Red'],
+            2 => ['data-color' => 'Yellow'],
+            3 => ['data-color' => 'Green'],
+        ],
+    ]);
+
+Example for a callable::
+
+    use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
+    // ...
+
     $builder->add('attending', ChoiceType::class, [
         'choices' => [
             'Yes' => true,