fix docs for soundboard_sound_update event

docs/api.rst

@@ -1354,8 +1354,10 @@ Soundboard
 
     .. versionadded:: 2.5
 
-    :param sound: The soundboard sound that was updated.
-    :type sound: :class:`SoundboardSound`
+    :param before: The soundboard sound before the update.
+    :type before: :class:`SoundboardSound`
+    :param after: The soundboard sound after the update.
+    :type after: :class:`SoundboardSound`
 
 
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