minor #5669 Better explanation of implicit exception response status code (hvt)

This PR was squashed before being merged into the 2.3 branch (closes #5669).

Discussion
----------

Better explanation of implicit exception response status code

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | none

Commits
-------

54f77d8 Better explanation of implicit exception response status code

Author: wouterj

reference/events.rst

@@ -215,10 +215,12 @@ and set a new ``Exception`` object, or do nothing::
     response won't work. If you want to overwrite the status code (which you
     should not without a good reason), set the ``X-Status-Code`` header::
 
-        $response = Response(
+        $response = new Response(
             'Error',
-            404 // ignored,
-            array('X-Status-Code' => 200)
+            404, // this status code will be ignored
+            array(
+                'X-Status-Code' => 200 // this status code will actually be sent to the client
+            )
         );
 
 .. seealso::