Correct retention_msecs value (#2232)

The `retention_msecs` takes a millisecond value not a seconds value, having checked and tested redis/commands/timeseries/commands.py is not adjusting seconds to milliseconds it is passing it through as is, therefore the statement in this doc is incorrect as it creates a time series with a retention period of 5 milliseconds not 5 seconds as stated.

Author: earthgecko

docs/redismodules.rst

@@ -134,7 +134,7 @@ These are the commands for interacting with the `RedisTimeSeries module <https:/
 
     import redis
     r = redis.Redis()
-    r.ts().create(2, retension_msecs=5)
+    r.ts().create(2, retension_msecs=5000)
 
 .. automodule:: redis.commands.timeseries.commands
     :members: TimeSeriesCommands