At the bottom of the markdown section in the options, there’s a link to ABC notation options.
It is listed in Joplin as https://paulrosen.github.io/abcjs/visual/render-abc-options.html
It is listed on that website as moved to https://docs.abcjs.net/visual/render-abc-options.html
As I say, not a big deal, but I thought I’d point it out.