minor #4403 Improved naming (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
----------

Improved naming

| Q   | A
| --- | ---
| Doc fix? | yes
| New docs? | no
| Applies to | all
| Fixed tickets | -

I always found this very confusing. Today, I decided to try to tackle it. It's hard to explain correctly using not that many words. I would like to hear other suggestions if you think those are better :)

Commits
-------

2665e1f Improved naming

components/dependency_injection/tags.rst

@@ -153,7 +153,7 @@ custom tag::
             $taggedServices = $container->findTaggedServiceIds(
                 'acme_mailer.transport'
             );
-            foreach ($taggedServices as $id => $attributes) {
+            foreach ($taggedServices as $id => $tags) {
                 $definition->addMethodCall(
                     'addTransport',
                     array(new Reference($id))
@@ -178,7 +178,7 @@ run when the container is compiled::
     use Symfony\Component\DependencyInjection\ContainerBuilder;
 
     $container = new ContainerBuilder();
-    $container->addCompilerPass(new TransportCompilerPass);
+    $container->addCompilerPass(new TransportCompilerPass());
 
 .. note::
 
@@ -291,8 +291,8 @@ use this, update the compiler::
             $taggedServices = $container->findTaggedServiceIds(
                 'acme_mailer.transport'
             );
-            foreach ($taggedServices as $id => $tagAttributes) {
-                foreach ($tagAttributes as $attributes) {
+            foreach ($taggedServices as $id => $tags) {
+                foreach ($tags as $attributes) {
                     $definition->addMethodCall(
                         'addTransport',
                         array(new Reference($id), $attributes["alias"])
@@ -302,7 +302,7 @@ use this, update the compiler::
         }
     }
 
-The trickiest part is the ``$attributes`` variable. Because you can use the
-same tag many times on the same service (e.g. you could theoretically tag
-the same service 5 times with the ``acme_mailer.transport`` tag), ``$attributes``
-is an array of the tag information for each tag on that service.
+The double loop may be confusing. This is because a service can have more than one
+tag. You tag a service twice or more with the ``acme_mailer.transport`` tag. The
+second foreach loop iterates over the ``acme_mailer.transport`` tags set for the
+current service and gives you the attributes.