minor #10328 [flex] use latest skeleton version in example (dbu)

This PR was merged into the 4.1 branch.

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[flex] use latest skeleton version in example

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0db429e use latest version in example

Author: javiereguiluz

setup/flex.rst

@@ -111,7 +111,7 @@ Symfony application by executing the following command:
 
 .. code-block:: terminal
 
-    $ composer create-project symfony/skeleton:3.4.* my-project
+    $ composer create-project symfony/skeleton:4.1.* my-project
 
 .. note::