[EventDispatcher] Show partial matching for debug:event-dispatcher

Author: Nyholm

event_dispatcher.rst

@@ -322,6 +322,17 @@ its name:
 
     $ php bin/console debug:event-dispatcher kernel.exception
 
+.. versionadded:: 5.3
+
+    You can also find listeners to event names partially matching a string. Example
+    to show all events and their listeners related to ``kernel``, your app or Security:
+
+    .. code-block:: terminal
+
+        $ php bin/console debug:event-dispatcher kernel
+        $ php bin/console debug:event-dispatcher App
+        $ php bin/console debug:event-dispatcher Security
+
 The :doc:`new experimental Security </security/experimental_authenticators>`
 system adds an event dispatcher per firewall. Use the ``--dispatcher`` option to
 get the registered listeners for a particular event dispatcher: