minor #6111 Fixed a typo in the choice_label code example (ferdynator)

This PR was submitted for the master branch but it was merged into the 2.7 branch instead (closes #6111).

Discussion
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Fixed a typo in the choice_label code example

| Q             | A
| ------------- | ---
| Doc fix?   | Yes
| New docs? | No
| Applies to | >=2.7
| Fixed tickets |

Commits
-------

7f25299 Fixed a typo in the choice_label code example

Author: xabbuh

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

@@ -43,7 +43,7 @@ If your choice values are objects, then ``choice_label`` can also be a
         'choices' => array(
             new Status(Status::YES),
             new Status(Status::NO),
-            new Status::(Status::MAYBE),
+            new Status(Status::MAYBE),
         ),
         'choices_as_values' => true,
         'choice_label' => 'displayName',