Matt McNaughton
0a56b9db51
Going through the guestbook tutorial for the first time, the deployment configuration mentioned that whether my configuration included a DNS service would dictate which env value I used for the `GET_HOSTS_FROM` variable. According to https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/, k8s includes DNS by default starting with v1.3. Add this additional info to help the user better understand when DNS may/may not be enabled.