issue #37316 identifies typo in Features gate (removed) for RootCAConfigMap (GA), the feature gate was removed in v1.22 but this was mistakenly typed as 1.12
As the upstream code evolves, many feature gates (deprecated or GA'ed) are removed. That means they are no longer recognized by the Kubernetes components. This PR moves such feature gates into a dedicated page for reference so that we won't bother revisit them again for future releases.