lockExclusiveAlice.pu: add comment about close and not save.

doc/diagram/lockExclusiveAlice.pu

@@ -21,7 +21,7 @@ alt press 'save' or press 'save and close'
   deactivate dirty
   save -> Alice: status=succes,redirect=client
   |||
-else press 'form close' or press 'back'
+else press 'form close' or press 'back' and answer question 'Save? yes|no|cancel' with 'no'.
   Alice -> dirty: action=release
   dirty -> Alice: status=success