Update sentinel documentation to include masters

[zulander1]

When the client connects to sentinel, we are getting an error to include +sentinel|masters

Url: https://redis.io/docs/management/sentinel/ under the section Sentinel Access Control List authentication
'Lastly, for authenticating incoming client connections, you can create a Sentinel restricted user profile such as the following'

This line should be modified to :
127.0.0.1:5000> ACL SETUSER sentinel-user ON >user-password -@all +auth +client|getname +client|id +client|setname +command +hello +ping +role +sentinel|get-master-addr-by-name +sentinel|master +sentinel|myid +sentinel|replicas +sentinel|sentinels +sentinel|masters