Update object cache settings page with messaging for Redis socket

[harryjackson1221]

Currently, the object cache settings page when using redis mentions hostname / IP and port, but you can also use a redis socket, which is theoretically faster than using tcp.
https://redis.io/docs/management/optimization/benchmarks/#:~:text=Depending%20on%20the%20platform%2C%20unix,use%20the%20TCP%2FIP%20loopback.

Please add messaging here about using a socket, such as the following:

To use Multiple servers separate by a comma; e.g. 127.0.0.1:6379, domain.com:6379. For local Redis instances, use a socket to connect; e.g. /var/run/redis/redis.sock or /var/run/redis/redis.sock:0. To use TLS, prefix server with tls://

[villelaitila]

Small sidenote: same for Memcached would also be great.