Fix description incorrectly saying that parameter w specifies an upper range. w is actually a width. Proof:
print(bit32.extract(2^32-1, 3, 4)) -- prints 15, not 1.
Also indicate that the position is 0-based, and that the function will error if the selected range exceeds the allowed bounds.
Full documentation for the standard library, written from scratch by looking at the source code - so hopefully this is reasonably correct/precise.
Some of the function descriptions are probably too concise to be easily understandable - we can flesh this out in the future.
Some of the type specifications aren't using valid Luau syntax; in particular, I've used "function" or "table" in a few places as a human-friendly notion that any function/table suffices, and the iterator functions just say that they return <iterator> without being specific as to what the signature of the generator is.
Arseny Kapoulkine