It’s kinda ugly, but you can check the norns source which collects them all in one file. norns/ii_actions.lua at main · monome/norns · GitHub
Also, the primary way i recommend is by sending ii.<module_name>.help() to crow. you can do this in maiden with crow.send "ii.jf.help()" to get the Just Friends commands. If you want to see which devices crow supports, you can type crow.send "ii.help()" which will print a list of all supported ii devices (which you can then individually query for their commands).
But we should make a list somewhere! Would be nice if it auto-updated whenever crow had new additions though 