Little suggestion about the documentation of luaL_argerror

[David Demelier <demelier.david@...>]

Hello folks,

All my best for 2014 :-).

I just wanted to say that the documentation of luaL_argerror is a bit 
unclear. I needed to ask on #lua about this funtion. At a glance, we 
don't really know what is the arg parameter. Is it a Lua type? Or the 
parameter number?. Currently it is a number. I needed to write a little 
test to understand that.

I think it should be corrected to specify what `arg' is supposed to be.

Cheers,
David Demelier