Return "unknown command" error for unknown subcommands

Signed-off-by: Xiangxuan Liu <xiangxuan.liu@rightcapital.com>

cmd/helm/root.go

@@ -26,7 +26,6 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/tools/clientcmd"
 
-	"helm.sh/helm/v3/cmd/helm/require"
 	"helm.sh/helm/v3/internal/completion"
 	"helm.sh/helm/v3/internal/experimental/registry"
 	"helm.sh/helm/v3/pkg/action"
@@ -77,7 +76,6 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		Short:                  "The Helm package manager for Kubernetes.",
 		Long:                   globalUsage,
 		SilenceUsage:           true,
-		Args:                   require.NoArgs,
 		BashCompletionFunction: completion.GetBashCustomFunction(),
 	}
 	flags := cmd.PersistentFlags()