Fix:(issue_1689) Let markdown output behave similar to cli help output

Author: dearchap

docs.go

@@ -153,9 +153,14 @@ func prepareFlags(
 // flagDetails returns a string containing the flags metadata
 func flagDetails(flag DocGenerationFlag) string {
 	description := flag.GetUsage()
-	value := flag.GetValue()
-	if value != "" {
-		description += " (default: " + value + ")"
+	if flag.TakesValue() {
+		defaultText := flag.GetDefaultText()
+		if defaultText == "" {
+			defaultText = flag.GetValue()
+		}
+		if defaultText != "" {
+			description += " (default: " + defaultText + ")"
+		}
 	}
 	return ": " + description
 }