Fixed wrong version of symfony with composer install

Nek- · Nek- · commit 4567de5b8b18 · 2015-08-29T19:36:17.000+02:00
diff --git a/book/installation.rst b/book/installation.rst
@@ -146,7 +146,7 @@ version as the second argument of the ``create-project`` command:
 
 .. code-block:: bash
 
-    $ composer create-project symfony/framework-standard-edition my_project_name "2.3.*"
+    $ composer create-project symfony/framework-standard-edition my_project_name "2.7.*"
 
 .. tip::
 
