Remove reference to Redis sentinel from configuration docs

Signed-off-by: Raul <r.ferreira.fuentes@gmail.com>

config/config.sample.php

@@ -1405,10 +1405,7 @@ $CONFIG = [
 ],
 
 /**
- * Connection details for a Redis Cluster
- *
- * Only for use with Redis Clustering, for Sentinel-based setups use the single
- * server configuration above, and perform HA on the hostname.
+ * Connection details for a Redis Cluster.
  *
  * Redis Cluster support requires the php module phpredis in version 3.0.0 or
  * higher.