minor #20485 Update File.rst (corentingd)

This PR was merged into the 6.4 branch.

Discussion
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Update File.rst

This is my first ever contribution to the Symfony documentation !
The PR will replace mimeTypes parameters by "extension" and "extensions" in extensionMessage option of the File constraint.

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Commits
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775bab6 Update File.rst

Author: javiereguiluz

Diff for: reference/constraints/File.rst

@@ -314,7 +314,12 @@ Parameter                       Description
 The message displayed if the extension of the file is not a valid extension
 per the `extensions`_ option.
 
-.. include:: /reference/constraints/_parameters-mime-types-message-option.rst.inc
+==================== ==============================================================
+Parameter            Description
+==================== ==============================================================
+``{{ extension }}``  The extension of the given file
+``{{ extensions }}`` The list of allowed file extensions
+==================== ==============================================================
 
 ``mimeTypesMessage``
 ~~~~~~~~~~~~~~~~~~~~