document "CoreDNS by default in v1.11"

[neolit123]

this PR set the feature gate for CoreDNS to true by default:
kubernetes/kubernetes#63509

feature discussion:
kubernetes/enhancements#427

document the transition in the docs (mentioned in a lot of places).

task list:

• https://kubernetes.io/docs/tasks/administer-cluster/coredns/

---> PR sent and amended multiple times.
kubernetes/website#8697

• https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-init/

---> PR
kubernetes/website#8728

• https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-alpha/#cmd-phase-addon

---> PR kubernetes/website#8727

• https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/
• https://kubernetes.io/docs/setup/independent/troubleshooting-kubeadm.md

---> PR
kubernetes/website#8753

• https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/

discussion / proposal for changes:
https://docs.google.com/document/d/1RFAN8e0q_Zfyyz9ZYGB6m-vaArgAZsnrsbv8BaQdH8o/edit?usp=sharing

---> PR
kubernetes/website#8900

• https://kubernetes.io/docs/reference/setup-tools/kubeadm/implementation-details/

---> PR
kubernetes/website#8829

Kubernetes Features OSS tracking board (1.11 release):
https://docs.google.com/spreadsheets/d/16N9KSlxWwxUA2gV6jvuW9N8tPRHzNhu1-RYY4Y0RZLs/edit#gid=0

---

we are not touching the following DNS related pages:

• https://kubernetes.io/docs/tasks/administer-cluster/dns-horizontal-autoscaling/
• https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/
• https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/
• https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/

if you think that we should do otherwise, do tell.

[neolit123]

i was instructed to break this into separate PRs against website, which will complicate things a bit.
@luxas, @timothysc, @detiber, i will bump this space when a new change is made so that you can quickly comment / approve to get the process going.

first one:
kubernetes/website#8697

[johnbelamaric]

cc @rajansandeep

[rajansandeep]

@neolit123 Is it ok if I can help out with the documentation?

[neolit123]

@rajansandeep that would be much appreciated. thank you.

can you please verify that the non-kubeadm links above need any updates?
we kind of searched for "dns" and ended up with that list.

[rajansandeep]

@neolit123 Sure. I'll check.
There will be a separate PR for each link?

[neolit123]

@rajansandeep
so it was suggested to me to split them for easier review.

not necessarily separate PRs for all links, but perhaps we can create one for:
https://kubernetes.io/docs/tasks/administer-cluster/*
and one for:
https://kubernetes.io/docs/concepts/services-networking/*

[neolit123]

@rajansandeep

so the kubeadm related changes are mostly submitted as PRs now (list in first post).

i'm not sure you had a look at what has to be changed here:
https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/

i've created a google docs file to allow us to discuss this:
https://docs.google.com/document/d/1RFAN8e0q_Zfyyz9ZYGB6m-vaArgAZsnrsbv8BaQdH8o/edit?usp=sharing

please, have a look at my comments there.