incorrect placeholdes for leave/enter transitions

Both leave and enter transitions are related to particular places. The names of most verbose ones incorrectly stated ``[transition name]``. The name of the place being leaved/entered is used to generate the event name instead

Author: Alexander Marinov

workflow/usage.rst

@@ -184,15 +184,15 @@ events are dispatched:
 
 * ``workflow.leave``
 * ``workflow.[workflow name].leave``
-* ``workflow.[workflow name].leave.[transition name]``
+* ``workflow.[workflow name].leave.[place name]``
 
 * ``workflow.transition``
 * ``workflow.[workflow name].transition``
 * ``workflow.[workflow name].transition.[transition name]``
 
 * ``workflow.enter``
 * ``workflow.[workflow name].enter``
-* ``workflow.[workflow name].enter.[transition name]``
+* ``workflow.[workflow name].enter.[place name]``
 
 * ``workflow.announce``
 * ``workflow.[workflow name].announce``