[Compatibility Version] Document safe upgrade process with emulation-version

[siyuanfoundation]

This is a Feature Request
In addition to https://kubernetes.io/docs/tasks/administer-cluster/cluster-upgrade/, with the introduction of Compatibility Version it is possible to do a new more granular and safer 2-step upgrade process utilizing --emulated-version now.

What would you like to be added

We need to document

1. the benefits of doing 2-step upgrade (can be found in the KEP
2. the process of 2-step upgrade for the control plane
3. verification of each step by checking thefeature_enabled & version_info metrics.

Why is this needed

To make kubernetes upgrade safer as proposed by kubernetes/enhancements#4330

Comments

[k8s-ci-robot]

This issue is currently awaiting triage.

SIG Docs takes a lead on issue triage for this website, but any Kubernetes member can accept issues by applying the triage/accepted label.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[sgriffis]

I can work on this documentation.

/assign