minor: ChoiceType callable deprecation after/before seems wrong

Simperfit · Amrouche Hamza · commit 30814a54e447 · 2019-04-18T07:11:39.000+02:00
That is on me 3 years ago !
diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
@@ -302,14 +302,14 @@ Form
    Before:
 
    ```php
-   'choice_value' => new PropertyPath('range'),
+   'choice_value' => 'range',
    'choice_label' => 'strtoupper',
    ```
 
    After:
 
    ```php
-   'choice_value' => 'range',
+   'choice_value' => new PropertyPath('range'),
    'choice_label' => function ($choice) {
        return strtoupper($choice);
    },
