Update install process

Resources/doc/reference/installation.rst

@@ -37,7 +37,10 @@ Installation
 Download SonataAdminBundle and its dependencies to the ``vendor`` directory. You
 can use Composer for the automated procces.
 
-    php composer.phar require sonata-project/admin-bundle
+    php composer.phar require sonata-project/admin-bundle --no-update
+    php composer.phar require sonata-project/doctrine-orm-admin-bundle --no-update  # optional
+    php composer.phar require sonata-project/intl-bundle --no-update                # optional
+    php composer.phar update
 
 Next, be sure to enable this bundles in your AppKernel.php file: