Updates on service dependency

Author: supriya-premkumar

keps/sig-autoscaling/2702-graduate-hpa-api-to-GA/README.md

@@ -37,6 +37,7 @@ denote sections that are under active debate as follows:
 ## Table of Contents
 
 <!-- toc -->
+- [Release Signoff Checklist](#release-signoff-checklist)
 - [Summary](#summary)
 - [Motivation](#motivation)
   - [Goals](#goals)
@@ -51,13 +52,54 @@ denote sections that are under active debate as follows:
   - [Version Skew Strategy](#version-skew-strategy)
   - [Upgrade/Downgrade Strategy](#upgradedowngrade-strategy)
 - [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
-  - [Feature Enablement and Rollback](#feature-enablement-and-rollback)
+  - [Requirements for migration](#requirements-for-migration)
   - [Rollout, Upgrade and Rollback Planning](#rollout-upgrade-and-rollback-planning)
   - [Monitoring Requirements](#monitoring-requirements)
   - [Dependencies](#dependencies)
   - [Scalability](#scalability)
 - [Implementation History](#implementation-history)
 <!-- /toc -->
+## Release Signoff Checklist
+
+<!--
+**ACTION REQUIRED:** In order to merge code into a release, there must be an
+issue in [kubernetes/enhancements] referencing this KEP and targeting a release
+milestone **before the [Enhancement Freeze](https://git.k8s.io/sig-release/releases)
+of the targeted release**.
+
+For enhancements that make changes to code or processes/procedures in core
+Kubernetes—i.e., [kubernetes/kubernetes], we require the following Release
+Signoff checklist to be completed.
+
+Check these off as they are completed for the Release Team to track. These
+checklist items _must_ be updated for the enhancement to be released.
+-->
+
+Items marked with (R) are required *prior to targeting to a milestone / release*.
+
+- [ ] (R) Enhancement issue in release milestone, which links to KEP dir in [kubernetes/enhancements] (not the initial KEP PR)
+- [ ] (R) KEP approvers have approved the KEP status as `implementable`
+- [ ] (R) Design details are appropriately documented
+- [ ] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input (including test refactors)
+  - [ ] e2e Tests for all Beta API Operations (endpoints)
+  - [ ] (R) Ensure GA e2e tests for meet requirements for [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md)
+  - [ ] (R) Minimum Two Week Window for GA e2e tests to prove flake free
+- [ ] (R) Graduation criteria is in place
+  - [ ] (R) [all GA Endpoints](https://github.com/kubernetes/community/pull/1806) must be hit by [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md)
+- [ ] (R) Production readiness review completed
+- [ ] (R) Production readiness review approved
+- [ ] "Implementation History" section is up-to-date for milestone
+- [ ] User-facing documentation has been created in [kubernetes/website], for publication to [kubernetes.io]
+- [ ] Supporting documentation—e.g., additional design documents, links to mailing list discussions/SIG meetings, relevant PRs/issues, release notes
+
+<!--
+**Note:** This checklist is iterative and should be reviewed and updated every time this enhancement is being considered for a milestone.
+-->
+
+[kubernetes.io]: https://kubernetes.io/
+[kubernetes/enhancements]: https://git.k8s.io/enhancements
+[kubernetes/kubernetes]: https://git.k8s.io/kubernetes
+[kubernetes/website]: https://git.k8s.io/website
 
 ## Summary
 
@@ -359,6 +401,10 @@ and creating new ones, as well as about cluster-level services (e.g. DNS):
       - Impact of its outage on the feature:
       - Impact of its degraded performance or high-error rates on the feature:
 -->
+The HPA requires the `metrics.k8s.io` APIs to be available in the cluster to operate,This API is served by the Metrics Server,
+without Metrics Server autoscaling on resource metrics will not work. Without the a custom metrics adapter and the backing metric store running, custom
+and external metrics will not work. If there are multiple metrics defined and one is not available, scale up will
+continue but scale down will not (for safety).
 
 ### Scalability