Instead of just handing the manual over, you could say a brief reason of what is happening or at least the section to read in there. No sane developer that's just casually using lua is going to read a manual about floating point numbers to report something they thought could be a bug.
Perhaps not, and I'm not defending the practice, but it IS an annoyingly common thing to ask about, especially since it's not only not a bug in Lua, it's not a bug at all and it's not specific to Lua. It's something that every developer needs to know.
(Other practices I don't defend: top-posting in contravention of list etiquette.)