adding ->compile to parent services docs, adding missing use statements

Author: Grayson Koonce

components/dependency_injection/parentservices.rst

@@ -236,6 +236,7 @@ a parent for a service.
     .. code-block:: php
 
         use Symfony\Component\DependencyInjection\Definition;
+        use Symfony\Component\DependencyInjection\DefinitionDecorator;
         use Symfony\Component\DependencyInjection\Reference;
 
         // ...
@@ -265,6 +266,8 @@ a parent for a service.
             '%greeting_card_manager.class%'
         );
 
+        $container->compile();
+
 In this context, having a ``parent`` service implies that the arguments and
 method calls of the parent service should be used for the child services.
 Specifically, the setter methods defined for the parent service will be called
@@ -482,6 +485,7 @@ If you had the following config:
     .. code-block:: php
 
         use Symfony\Component\DependencyInjection\Definition;
+        use Symfony\Component\DependencyInjection\DefinitionDecorator;
         use Symfony\Component\DependencyInjection\Reference;
 
         // ...
@@ -505,6 +509,8 @@ If you had the following config:
             new Reference('another_filter')
         ));
 
+        $container->compile();
+
 In this example, the ``setFilter`` of the ``newsletter_manager`` service
 will be called twice, resulting in the ``$filters`` array containing both
 ``my_filter`` and ``another_filter`` objects. This is great if you just want