Huh — like the sound — is a new documentation plugin by Nick Hamze. It offers a little tooltip to your customer that enables easy to access documentation, right within the WordPress dashboard.
Having recently gone through some install processes, I found documentation a bit of a hurdle to find, and am currently digging this concept. Nick says he used a similar tool on his Shopify product and it has increased engagement.
Huh can reference any Markdown file — in the product or hosted elsewhere. So, you can ship the theme or plugin with a reference to a Markdown file on your Github account, and the buyer would get new documentation as you update it. This also intrigues me for non-documentation stuff, like important updates, upsells, etc.
Huh is on GitHub and free for anyone to play with. Huh is just one of the exciting things Nick is working on; he's investing heavily in several areas of WordPress products, so definitely keep an eye on his Secret Pizza Party website — the greatest named website ever, maybe.