Doco should have a section just for lua basics (eg, array/hash usage and api, etc). The Lua elements that are currently in the doco are ok, but it seems to be missing some language basics.
agreed! Specially for beginning student and general educational use.
Getting it in the actual documentation on the app might take a little time, as each update has to be approved by Apple.
In the meantime, there’s always the wiki. The page https://bitbucket.org/TwoLivesLeft/codea/wiki/LuaBasics (which is currently empty) would seem an ideal place for this.
The website <www.lua.org> has some resources, notably http://www.lua.org/pil/ (though note that this is the first edition) and http://www.lua.org/manual/5.1/