Fix some golint errors for packages in pkg/kubectl/cmd

Co-authored-by: Arijit Basu <sayanarijit@gmail.com>

pkg/kubectl/cmd/auth/auth.go

@@ -23,6 +23,7 @@ import (
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 )
 
+// NewCmdAuth returns an initialized Command instance for 'auth' sub command
 func NewCmdAuth(f cmdutil.Factory, streams genericclioptions.IOStreams) *cobra.Command {
 	// Parent command to which all subcommands are added.
 	cmds := &cobra.Command{