minor #14945 [Validator] Add a comma after the last array item in a multi-line array (wkania)

This PR was merged into the 4.4 branch.

Discussion
----------

[Validator] Add a comma after the last array item in a multi-line array

<!--

If your pull request fixes a BUG, use the oldest maintained branch that contains
the bug (see https://symfony.com/releases for the list of maintained branches).

If your pull request documents a NEW FEATURE, use the same Symfony branch where
the feature was introduced (and `5.x` for features of unreleased versions).

-->

Commits
-------

918671a [Validator] Add a comma after the last array item in a multi-line array

Author: OskarStark

validation/raw_values.rst

@@ -88,7 +88,7 @@ Validation of arrays is possible using the ``Collection`` constraint::
                 new Assert\Collection([
                     'slug' => [
                         new Assert\NotBlank(),
-                        new Assert\Type(['type' => 'string'])
+                        new Assert\Type(['type' => 'string']),
                     ],
                     'label' => [
                         new Assert\NotBlank(),