Gatekeeper migration docs are inaccurate

https://repo1.dso.mil/big-bang/product/packages/kyverno-policies/-/blob/72696f6fe0bb0f6313192bf0cfa0a1fe0e9a1ce2/docs/gatekeeper.md#L38

restrict-sysctl should be changed to restrict-sysctls (for example: https://repo1.dso.mil/big-bang/product/packages/kyverno-policies/-/blob/3.3.4-bb.3/chart/values.yaml?ref_type=tags#L481)