minor #20244 [DependencyInjection] Fix typo filename (juukie)

This PR was submitted for the 7.1 branch but it was merged into the 6.4 branch instead.

Discussion
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[DependencyInjection] Fix typo filename

Make filename match classname

Commits
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19ee7d2 Fix typo filename

Author: javiereguiluz

service_container.rst

@@ -1434,7 +1434,7 @@ Let's say you have the following functional interface::
 You also have a service that defines many methods and one of them is the same
 ``format()`` method of the previous interface::
 
-    // src/Service/MessageFormatterInterface.php
+    // src/Service/MessageUtils.php
     namespace App\Service;
 
     class MessageUtils