Document how to configure DNS in Hostport / NodePort mode

[tamalsaha]

Voyager should manage the Route 53 settings for having all of the nodes running HAProxy in the DNS A record.

From our Slack: "It would be great if this was added as a mode of operation for Voyager. I may be the only person on the planet that is on Amazon but can't use an ELB, though. Well, maybe also these guys: https://www.loggly.com/blog/why-aws-route-53-over-elastic-load-balancing/ "

[tamalsaha]

external-dns project only works with LoadBalancer, NodePort is not supported. https://github.com/kubernetes-incubator/external-dns/blob/master/docs/faq.md#which-kubernetes-objects-are-supported

[tamalsaha]

We can use https://github.com/appscode/go-dns to deal with any generic DNS server.

[greg-jaunt]

Kops dns-controller may also handle this:
https://github.com/kubernetes/kops/tree/master/dns-controller

Out-of-date, but better docs here:
https://github.com/kubernetes-incubator/external-dns/blob/master/docs/legacy/kops-dns-controller.md

[tamalsaha]

Setting metadata.annotations.ingress.appscode.com/annotations-pod: '{"dns.alpha.kubernetes.io/external": "name.domain.com"}' exposes the HAProxy nodes perfectly as long as you have dns-controller running (comes with Kops clusters).

[tamalsaha]

Merged into #355