The document of lua_remove is out of date

[Yan Li <yl.mechanize@...>]

I find the lua54 document of lua_remove is still [-1, +0, –], which is wrong. It should be [-1, +0, e], According to `#define lua_remove(L,idx)    (lua_rotate(L, (idx), -1), lua_pop(L, 1))`.