Adding a linter for Kubernetes v1.21
Changes are here : v2.5.0...v2.6.0
please see https://github.com/kubernetes/klog/tree/master/hack/tools/logcheck
Changes are here : v2.5.0...v2.6.0
please see https://github.com/kubernetes/klog/tree/master/hack/tools/logcheck