[feature request] Show in-progress exercises on home page

As someone with incomplete exercises across multiple tracks, it’d be a good nudge for me if the Exercism home page could suggest one of those exercises to keep working on. It could be a random in-progress exercise from either the least or most recently touched track. Currently, I’d have to go to the tracks page, pick a track, and then pick an incomplete exercise so it’s easy for me to forget about them.