Ask HN: Best way to create a cheatsheet?

Hi, I want to create a cheatsheet. It should be displayed as concisely as possible. I would also like it to be checked into git. So I can version it and others can contribute their knowledge. It can easily evolve as new items can be added due to changes in the target language/software.

What is the best way to do this? Is there an open source version available?

The ideal case would be where the items can be added to a markdown or similar file and the cheatsheet can be generated using some generator.