fix async_wait_message docstring

Author: nklokk

ydb/_topic_reader/topic_reader_sync.py

@@ -79,7 +79,7 @@ def async_wait_message(self) -> concurrent.futures.Future:
         Returns a future, which will complete when the reader has at least one message in queue.
         If the reader already has a message - the future will complete immediately.
 
-        A message may expire before it gets read so that the attempt to receive the massage will fail
+        A message may expire before it gets read so that the attempt to receive the message will fail
         despite the future has signaled about its availability.
         """
         self._check_closed()