Implemented the suggestions made by Christian and Wouter

Author: javiereguiluz

cookbook/bundles/installation.rst

@@ -44,7 +44,7 @@ version, include it as the second argument of the `composer require`_ command:
 
 .. code-block:: bash
 
-    $ composer require friendsofsymfony/user-bundle "~2.0@dev"
+    $ composer require friendsofsymfony/user-bundle "~2.0"
 
 B) Enable the Bundle
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