minor #19330 [EventDispatcher] Move note below and add examples (mikocevar)

This PR was submitted for the 6.4 branch but it was merged into the 5.4 branch instead.

Discussion
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[EventDispatcher] Move note below and add examples

I find it more user-friendly to see examples when explaining alternative solutions. The note was also moved lower to give the reader first the context of how the Custom Event with arguments is created, before explaining the alternative solution without arguments.

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Commits
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6f02336 Move note below and add examples

Author: javiereguiluz

components/event_dispatcher.rst

@@ -274,15 +274,6 @@ order. Start by creating this custom event class and documenting it::
 
 Each listener now has access to the order via the ``getOrder()`` method.
 
-.. note::
-
-    If you don't need to pass any additional data to the event listeners, you
-    can also use the default
-    :class:`Symfony\\Contracts\\EventDispatcher\\Event` class. In such case,
-    you can document the event and its name in a generic ``StoreEvents`` class,
-    similar to the :class:`Symfony\\Component\\HttpKernel\\KernelEvents`
-    class.
-
 Dispatch the Event
 ..................
 
@@ -306,6 +297,32 @@ Notice that the special ``OrderPlacedEvent`` object is created and passed to
 the ``dispatch()`` method. Now, any listener to the ``OrderPlacedEvent::class``
 event will receive the ``OrderPlacedEvent``.
 
+.. note::
+
+    If you don't need to pass any additional data to the event listeners, you
+    can also use the default
+    :class:`Symfony\\Contracts\\EventDispatcher\\Event` class. In such case,
+    you can document the event and its name in a generic ``StoreEvents`` class,
+    similar to the :class:`Symfony\\Component\\HttpKernel\\KernelEvents`
+    class::
+
+        namespace App\Event;
+
+        class StoreEvents {
+
+            /**
+            * @Event("Symfony\Contracts\EventDispatcher\Event")
+            */
+            public const ORDER_PLACED = 'order.placed';
+        }
+
+    And use the :class:`Symfony\\Contracts\\EventDispatcher\\Event` class to
+    dispatch the event::
+
+        use Symfony\Contracts\EventDispatcher\Event;
+
+        $this->eventDispatcher->dispatch(new Event(), StoreEvents::ORDER_PLACED);
+
 .. _event_dispatcher-using-event-subscribers:
 
 Using Event Subscribers