minor #20771 [Mercure] Update mercure.rst (94noni)

This PR was submitted for the 7.2 branch but it was merged into the 6.4 branch instead.

Discussion
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[Mercure] Update mercure.rst

some minor improvement related to mercure and JS logic (I use both with stimulus)

Commits
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585fdb4 Update mercure.rst

Author: javiereguiluz

mercure.rst

@@ -282,6 +282,11 @@ URL in a dedicated HTML element:
     {{ mercure('https://example.com/books/1')|json_encode(constant('JSON_UNESCAPED_SLASHES') b-or constant('JSON_HEX_TAG'))|raw }}
     </script>
 
+    <!-- with Stimulus -->
+    <div {{ stimulus_controller('my-controller', {
+        mercureUrl: mercure('https://example.com/books/1'),
+    }) }}>
+
 Then retrieve it from your JS file:
 
 .. code-block:: javascript
@@ -290,6 +295,9 @@ Then retrieve it from your JS file:
     const eventSource = new EventSource(url);
     // ...
 
+    // with Stimulus
+    this.eventSource = new EventSource(this.mercureUrlValue);
+
 Mercure also allows subscribing to several topics,
 and to use URI Templates or the special value ``*`` (matched by all topics)
 as patterns:
@@ -407,7 +415,7 @@ of the ``Update`` constructor to ``true``::
             $update = new Update(
                 'https://example.com/books/1',
                 json_encode(['status' => 'OutOfStock']),
-                true // private
+                private: true
             );
 
             // Publisher's JWT must contain this topic, a URI template it matches or * in mercure.publish or you'll get a 401
@@ -704,6 +712,8 @@ enable it::
     :alt: The Mercure panel of the Symfony Profiler, showing information like time, memory, topics and data of each message sent by Mercure.
     :class: with-browser
 
+The Mercure hub itself provides a debug tool that can be enabled and available on `/.well-known/mercure/ui/`
+
 Async dispatching
 -----------------