Vim keybinding support details

It's great that HackMD has Vim keybindings. Of course it's not full-featured vim, as is evident when doing a search (it says Javascript regex).

I'd like to know what package you're using to implement the Vim keybindings, so that I know what is and what isn't supported. Couldn't find it quickly, but stopped short of searching the code base..

Step 1: Just say what you're using, presumably the package explains what is and isn't supported
Step 2: Put a bit of information in the help section to tell people what is and isn't supported, without having to dive into Github issues.