minor #9119 Update translation.rst (jakumi)

This PR was submitted for the 4.0 branch but it was squashed and merged into the 2.7 branch instead (closes #9119).

Discussion
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Update translation.rst

`MessageSelector` doesn't implement `Symfony\Component\Translation\Formatter\MessageFormatterInterface` - the expected second parameter for `Translator::__construct`, which is generated if not provided anyway. removing the second parameter in the example seems like the best option imho.

Commits
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33ac660 Update translation.rst

Author: javiereguiluz

components/translation.rst

@@ -34,9 +34,8 @@ The constructor of the ``Translator`` class needs one argument: The locale.
 .. code-block:: php
 
     use Symfony\Component\Translation\Translator;
-    use Symfony\Component\Translation\MessageSelector;
 
-    $translator = new Translator('fr_FR', new MessageSelector());
+    $translator = new Translator('fr_FR');
 
 .. note::