add tls configuration and instructions

[mrkurt]

[codepope]

Readme config doesn't match up in naming:

/certs
   /redis-server.crt
   /redis-server.key
   /rootCA.crt
/redis-client.crt
   /redis-client.key

Then, we can pop on into the redis.conf to configure TLS:

tls-port 7379
tls-cert-file /etc/certs/server.pem
tls-key-file /etc/certs/server-key.pem
tls-ca-cert-file /etc/certs/rootCA.crt