fix typo

docs/userguide/tasks.rst

@@ -902,7 +902,7 @@ Example that stores results manually:
     @app.task(bind=True)
     def get_tweets(self, user):
         timeline = twitter.get_timeline(user)
-        self.update_state(sate=states.SUCCESS, meta=timeline)
+        self.update_state(state=states.SUCCESS, meta=timeline)
         raise Ignore()
 
 .. _task-semipred-reject: