minor symfony#9442 Update setup.rst (NAYZO)

This PR was merged into the 4.0 branch.

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Update setup.rst

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58fe989 Update setup.rst

Author: javiereguiluz

setup.rst

@@ -122,7 +122,7 @@ vulnerability. Run this command to install it in your application:
 .. code-block:: terminal
 
     $ cd my-project/
-    $ composer require sec-checker
+    $ composer require sec-checker --dev
 
 From now on, this utility will be run automatically whenever you install or
 update any dependency in the application. If a dependency contains a vulnerability,