minor #8256 Update logger service channel name (dubbs, javiereguiluz)

This PR was merged into the 3.3 branch.

Discussion
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Update logger service channel name

This looks like it should be `acme` instead of `app`.

Commits
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7366b2d Renamed the channel to "app"
e016a91 Update dic_tags.rst

Author: javiereguiluz

reference/dic_tags.rst

@@ -658,7 +658,7 @@ channel when injecting the logger in a service.
             AppBundle\Log\CustomLogger:
                 arguments: ['@logger']
                 tags:
-                    - { name: monolog.logger, channel: acme }
+                    - { name: monolog.logger, channel: app }
 
     .. code-block:: xml
 
@@ -671,7 +671,7 @@ channel when injecting the logger in a service.
             <services>
                 <service id="AppBundle\Log\CustomLogger">
                     <argument type="service" id="logger" />
-                    <tag name="monolog.logger" channel="acme" />
+                    <tag name="monolog.logger" channel="app" />
                 </service>
             </services>
         </container>
@@ -683,7 +683,7 @@ channel when injecting the logger in a service.
 
         $container->register(CustomLogger::class)
             ->addArgument(new Reference('logger'))
-            ->addTag('monolog.logger', array('channel' => 'acme'));
+            ->addTag('monolog.logger', array('channel' => 'app'));
 
 .. tip::