minor #32382 Fix phpdocs (fabpot)

This PR was merged into the 4.4 branch.

Discussion
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Fix phpdocs

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Backported from #32286

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Commits
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4acddef91b fixed phpdocs

Author: fabpot

Definition/ArrayNode.php

@@ -141,7 +141,7 @@ public function setPerformDeepMerging($boolean)
     }
 
     /**
-     * Whether extra keys should just be ignore without an exception.
+     * Whether extra keys should just be ignored without an exception.
      *
      * @param bool $boolean To allow extra keys
      * @param bool $remove  To remove extra keys