Updated dns/README after implementing automation
Updated dns/README after implementing automation

As there is currently no need to manually update dnses and it's done
automatically (prow manages that), I updated the documentation to
reflect the changes

Signed-off-by: Bart Smykla <05a61b7a17440ad59b313e4d55e2ded5a86010f0@vmware.com>

thockin/k8s.io,kubernetes/k8s.io,thockin/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io,thockin/k8s.io,thockin/k8s.io,kubernetes/k8s.io