commands: replace <default> keyword with <<default>>

This way if we use <default> in description (we use thigns like <hash>
already), it won't conflict and modify the description in unwanted way.

License: MIT
Signed-off-by: Jakub Sztandera <kubuxu@protonmail.ch>

option.go

@@ -47,8 +47,8 @@ func (o *option) Description() string {
 		o.description += "."
 	}
 	if o.defaultVal != nil {
-		if strings.Contains(o.description, "<default>") {
-			return strings.Replace(o.description, "<default>",
+		if strings.Contains(o.description, "<<default>>") {
+			return strings.Replace(o.description, "<<default>>",
 				fmt.Sprintf("Default: %v.", o.defaultVal), -1)
 		} else {
 			return fmt.Sprintf("%s Default: %v.", o.description, o.defaultVal)