Updated docs

Author: chandr-andr

README.md

@@ -71,9 +71,10 @@ Brokers parameters:
 RedisAsyncResultBackend parameters:
 * `redis_url` - url to redis.
 * `keep_results` - flag to not remove results from Redis after reading.
-* `result_ex_time` - expire time in seconds (by default - 1 minute)
+* `result_ex_time` - expire time in seconds (by default - not specified)
 * `result_px_time` - expire time in milliseconds (by default - not specified)
-> IMPORTANT: You must specify either `result_ex_time` or `result_px_time`.  
+> IMPORTANT: **It is highly recommended to use expire time ​​in RedisAsyncResultBackend**  
+> You must specify either `result_ex_time` or `result_px_time`.  
 >```python
 ># First variant
 >redis_async_result = RedisAsyncResultBackend(