minor #5445 Reworded the explanation about the kernel.event_listener tag (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
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Reworded the explanation about the kernel.event_listener tag

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | #4680

Commits
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edd3875 Restored some content deleted by mistake
58d6346 Minor rewording
db7b78f Reworded the explanation about the kernel.event_listener tag

Author: weaverryan

reference/dic_tags.rst

@@ -476,8 +476,9 @@ kernel.event_listener
 
 **Purpose**: To listen to different events/hooks in Symfony
 
-This tag allows you to hook your own classes into Symfony's process at different
-points.
+During the execution of a Symfony application, different events are triggered
+and you can also dispatch custom events. This tag allows you to *hook* your own
+classes into any of those events.
 
 For a full example of this listener, read the :doc:`/cookbook/event_dispatcher/event_listener`
 cookbook entry.