Add note about not using autoconfigure

Author: Neirda24

service_container/service_subscribers_locators.rst

@@ -140,6 +140,11 @@ count and iterate over the services of the locator::
     The :class:`Symfony\\Contracts\\Service\\ServiceCollectionInterface` was
     introduced in Symfony 7.1.
 
+Without autoconfiguration
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you are not using autoconfiguration you need to require either ``Psr\Container\ContainerInterface`` or ``Symfony\Contracts\Service\ServiceProviderInterface`` as a ``__construct`` argument or as a method call like ``setContainer(Psr\Container\ContainerInterface $container)``.
+
 Including Services
 ------------------