I would find any source of displaying a message to the end user. Most applications have some data that comes from a remote server, whether it's on the home scr

I would find any source of displaying a message to the end user. Most applications have some data that comes from a remote server, whether it's on the home screen, any kind of announcements screen, server-sourced error messages, etc. I would use that to communicate an update is available, with a handy link.