Replace static version constraint (2.4.4)

...with a smarter one. Using Composer's tilde operator (~), also known
as the next significant release constraint, we instruct composer to use
at least Symfony 2.3, but not 3.0 or higher.

cookbook/workflow/new_project_git.rst

@@ -24,7 +24,7 @@ git repository:
 
    .. code-block:: bash
 
-        $ php composer.phar create-project symfony/framework-standard-edition path/ 2.4.4
+        $ php composer.phar create-project symfony/framework-standard-edition path/ ~2.3
 
    Composer will now download the Standard Distribution along with all of the
    required vendor libraries. For more information about downloading Symfony using