improve env and config example

help.go

@@ -694,6 +694,21 @@ func docFullSubcommands(cmd Cmd, conf Config, level int) []Entry {
 	return e
 }
 
+func exampleValue(o bind.Field) string {
+	switch o.Type() {
+	case bind.Bool:
+		return "true"
+	case bind.String:
+		return o.Name()
+	case bind.Duration:
+		return "42s"
+	case bind.Time:
+		return "Thu Jan 15 23:11:53 CET 2026"
+	default:
+		return "42"
+	}
+}
+
 func docEnv(cmd Cmd, level int) []Entry {
 	// env will not work if the app has a non-standard name:
 	if !commandNameExpression.MatchString(cmd.name) {
@@ -714,11 +729,7 @@ func docEnv(cmd Cmd, level int) []Entry {
 	e = append(e, Indent(Title(level+2, "Example environment variable:"), 4, 0))
 	option := options[0]
 	name := strcase.ToScreamingSnake(fmt.Sprintf("%s-%s", cmd.name, option.Name()))
-	value := "42"
+	value := exampleValue(option)
-	if option.Type() == bind.Bool {
-		value = "true"
-	}
-
 	e = append(e, Indent(CodeBlock(fmt.Sprintf("%s=%s", name, value)), 4, 0))
 	return e
 }
@@ -767,7 +778,7 @@ func docConfig(cmd Cmd, conf Config, level int) []Entry {
 
 	option := options[0]
 	name := option.Name()
-	value := "42"
+	value := exampleValue(option)
 	if option.Type() == bind.Bool {
 		value = "true"
 	}