minor #7581 Update event_dispatcher.rst (atailouloute, javiereguiluz)

This PR was merged into the 2.7 branch.

Discussion
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Update event_dispatcher.rst

I think it's better to say `the event class instance` instead of `the event class`, because when dispatching an event we send an instance of the event class

Commits
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6613f04 "class instance" -> "object"
ca51b87 Update event_dispatcher.rst

Author: wouterj

components/event_dispatcher.rst

@@ -182,7 +182,7 @@ the ``Event`` object as the single argument::
         }
     }
 
-The ``$event`` argument is the event class that was passed when dispatching the
+The ``$event`` argument is the event object that was passed when dispatching the
 event. In many cases, a special event subclass is passed with extra
 information. You can check the documentation or implementation of each event to
 determine which instance is passed.