Document URL:
https://docs.openshift.com/container-platform/4.8/updating/updating-cluster-within-minor.html#prerequisites

Section Number and Name:
No numerated

Describe the issue:
As per enhancement of upstream Kubernetes:
[Introducing RootCAConfigMap](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.20.md#introducing-rootcaconfigmap) which is Beta for 1.20 and GA for K8s 1.21, required to have 2 spare configmaps on each namespace otherwise pod affected remains in "ContainerCreating" status affecting the service availability on upgrade to OCP 4.8

Suggestions for improvement:
Add information as prerequisite for Upgrade to OCP 4.8

Additional information:
Solution: https://access.redhat.com/solutions/6958562
Upstream Feature Gates: https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/