minor #12510 Fixed grammar error in docblock (gerryvdm)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #12510).

Discussion
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Fixed grammar error in docblock

Commits
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ba8d937 Fixed grammar error in docblock

src/Symfony/Component/Config/ConfigCache.php

@@ -90,7 +90,7 @@ class ConfigCache
      * @param string              $content  The content to write in the cache
      * @param ResourceInterface[] $metadata An array of ResourceInterface instances
      *
-     * @throws \RuntimeException When cache file can't be wrote
+     * @throws \RuntimeException When cache file can't be written
      */
     public function write($content, array $metadata = null)
     {