minor #7911 [DependencyInjection] Fix decorating service definition (michaelperrin)

This PR was merged into the 2.7 branch.

Discussion
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[DependencyInjection] Fix decorating service definition

There is an error, particularly on the YAML definition where the `decoration_inner_name` option is not defined on the correct service. It should be defined on the decorating service, and not on the decorated service.

The XML definition was correct, but was lacking some properties to make things clearer.

There PHP definition was not using the correct name of the decorated service.

I have fixed the indentation as well on the YAML configuration.

Commits
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dabf122 Fix decorating service definition

Author: xabbuh

service_container/service_decoration.rst

@@ -61,10 +61,10 @@ a reference of the old one  as ``app.decorating_mailer.inner``:
             # ...
 
             app.decorating_mailer:
-              class:     AppBundle\DecoratingMailer
-              decorates: app.mailer
-              arguments: ['@app.decorating_mailer.inner']
-              public:    false
+                class:     AppBundle\DecoratingMailer
+                decorates: app.mailer
+                arguments: ['@app.decorating_mailer.inner']
+                public:    false
 
     .. code-block:: xml
 
@@ -128,7 +128,7 @@ convention, the old ``app.mailer`` service is renamed to
         .. code-block:: yaml
 
             services:
-                app.mailer:
+                app.decorating_mailer:
                     # ...
                     decoration_inner_name: app.decorating_mailer.wooz
                     arguments: ['@app.decorating_mailer.wooz']
@@ -144,7 +144,11 @@ convention, the old ``app.mailer`` service is renamed to
                     <!-- ... -->
 
                     <service
+                        id="app.decorating_mailer"
+                        class="AppBundle\DecoratingMailer"
+                        decorates="app.mailer"
                         decoration-inner-name="app.decorating_mailer.wooz"
+                        public="false"
                     >
                         <argument type="service" id="app.decorating_mailer.wooz" />
                     </service>
@@ -158,7 +162,7 @@ convention, the old ``app.mailer`` service is renamed to
             use Symfony\Component\DependencyInjection\Reference;
 
             $container->register('app.decorating_mailer', DecoratingMailer::class)
-                ->setDecoratedService('foo', 'app.decorating_mailer.wooz')
+                ->setDecoratedService('app.mailer', 'app.decorating_mailer.wooz')
                 ->addArgument(new Reference('app.decorating_mailer.wooz'))
                 // ...
             ;