Update best_practices.rst

Author: amine-betari

best_practices.rst

@@ -234,7 +234,7 @@ the fact that a controller should always return a ``Response`` object.
 Use Dependency Injection to Get Services
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-If you extend the base ``AbstractController``, you can't access services
+If you extend the base ``AbstractController``, you can't access private services
 directly from the container via ``$this->container->get()`` or ``$this->get()``.
 Instead, you must use dependency injection to fetch services by
 :ref:`type-hinting action method arguments <controller-accessing-services>` or