minor #13305 [DI] Improve an example about automatic tags and bundles (javiereguiluz)

This PR was merged into the 4.4 branch.

Discussion
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[DI] Improve an example about automatic tags and bundles

I just needed this inside a bundle ... and the example only shows a Symfony app ... so this was confusing to me.

But if you prefer to not expand this example, it's OK to close this. Thanks!

Commits
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6ab0fdd [DI] Improve an example about automatic tags and bundles

Author: javiereguiluz

service_container/tags.rst

@@ -117,8 +117,9 @@ If you want to apply tags automatically for your own services, use the
 
 
 For more advanced needs, you can define the automatic tags using the
-:method:`Symfony\\Component\\DependencyInjection\\ContainerBuilder::registerForAutoconfiguration`
-method in an :doc:`extension </bundles/extension>` or from your kernel::
+:method:`Symfony\\Component\\DependencyInjection\\ContainerBuilder::registerForAutoconfiguration` method.
+
+In a Symfony application, call this method in your kernel class::
 
     // src/Kernel.php
     class Kernel extends BaseKernel
@@ -133,6 +134,22 @@ method in an :doc:`extension </bundles/extension>` or from your kernel::
         }
     }
 
+In a Symfony bundle, call this method in the ``load()`` method of the
+:doc:`bundle extension class </bundles/extension>`::
+
+    // src/DependencyInjection/MyBundleExtension.php
+    class MyBundleExtension extends Extension
+    {
+        // ...
+
+        public function load(array $configs, ContainerBuilder $container)
+        {
+            $container->registerForAutoconfiguration(CustomInterface::class)
+                ->addTag('app.custom_tag')
+            ;
+        }
+    }
+
 Creating custom Tags
 --------------------