App manual and info included in the app

[Cwpute]

It's when i visited this github that i discovered i could long-press them to personalize the dice-sets at the bottom of the screen.

It would be useful to include some sort of "how to" directly into the app, with that information specifically, and others that might serve the user.

Also, having an "About" page directly in-app is pretty common nowadays. It usually includes the license for the app, the name of the maintainers, contributors, links for contributions if they're wolcome etc…