Document Redis Sentinel support for multiple sentinel addresses

[MyMirelHub]

What content needs to be created or modified?

The redisHost field description should clarify that comma-separated addresses also work for Redis Sentinel mode (not just cluster mode). Additionally, add a brief Redis Sentinel configuration section.

Where should the new material be placed?

Update all Redis component docs that have the failover and sentinelMasterName fields

The associated pull request from dapr/dapr, dapr/components-contrib, or other Dapr code repos

Additional context User outage revealed undocumented support for multiple sentinel addresses via comma-separated values in redisHost

[MyMirelHub]

/assign