Updated required version in docs (#3914)

Resources/doc/getting_started/installation.rst

@@ -12,7 +12,7 @@ following command to download the latest stable version of this bundle:
 
 .. code-block:: bash
 
-    $ composer require sonata-project/admin-bundle "2.3.*"
+    $ composer require sonata-project/admin-bundle
 
 This command requires you to have Composer installed globally, as explained in
 the `installation chapter`_ of the Composer documentation.
@@ -35,7 +35,7 @@ to download the SonataDoctrineORMAdminBundle, execute the following command:
 
 .. code-block:: bash
 
-    $ composer require sonata-project/doctrine-orm-admin-bundle "2.3.*"
+    $ composer require sonata-project/doctrine-orm-admin-bundle
 
 .. tip::