Can you add a debug mode？

[junmaqiang]

Hope to add a mode so that all upgrades can be seen. Now it's a black box, no way to track it

	_, err := selfupdate.Manage(config) 
	if err != nil {
		fmt.Println("ERROR: ", err)
		return
	}

[Bluebugs]

selfupdate.Manage is largely asynchronous. That's why we provide logging interface:
selfupdate.LogError, selfupdate.LogInfo and selfupdate.LogDebug . You just need to set the logging function you want to it and you are good to go. Is that good enough for your use case?