add doc command

cmd/doc.go

@@ -0,0 +1,34 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/cobra/doc"
+)
+
+// configureCmd represents the configure command
+var genDocCmd = &cobra.Command{
+	Use:    "gendoc",
+	Hidden: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		docType, err := cmd.Flags().GetString("type")
+		if err != nil {
+			return err
+		}
+		cmd.DisableAutoGenTag = true
+		switch docType {
+		case "markdown":
+			return doc.GenMarkdownTree(rootCmd, "doc")
+		case "man":
+			return doc.GenManTree(rootCmd, nil, "man")
+		default:
+			return fmt.Errorf("Unknown type: %v", docType)
+		}
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(genDocCmd)
+	genDocCmd.Flags().StringP("type", "t", "markdown", "what to generate, markdown or man")
+}