docs/api.rst: update wait_for_slot_event

Author: Sowards

docs/api.rst

@@ -63,12 +63,12 @@ Classes
 
             Waits for a slot event such as a token insertion or removal to occur.
 
-            Returns the slot id where the event was detected. If not blocking and no slot events were detected
+            Returns the Slot on which the event was detected. If not blocking and no slot events were detected
             :class:`pkcs11.exceptions.NoEvent` is raised.
 
             :param blocking: If true, the thread will block.
 
-            :rtype: int
+            :rtype: Slot
 
         .. method:: reinitialize()