Disable alpha kustomize commands by default.

- enable alpha commands with env KUSTOMIZE_SHOW_ALPHA_COMMANDS=true

cmd/config/cmds/example_test.go

@@ -4,13 +4,18 @@
 package cmds_test
 
 import (
+	"os"
+
 	"github.com/spf13/cobra"
 	"sigs.k8s.io/kustomize/cmd/config/cmds"
+	"sigs.k8s.io/kustomize/kyaml/commandutil"
 )
 
 // ExampleNewConfigCommand demonstrates how to embed the config command as a command inside
 // another group.
 func ExampleNewConfigCommand() {
+	// enable the config commands
+	os.Setenv(commandutil.EnableAlphaCommmandsEnvName, "true")
 	var root = &cobra.Command{
 		Use:   "my-cmd",
 		Short: "My command.",