Summarize how the implementation works

[roryokane]

This might be of interest to viewers of the project. Especially the “typed array” link, for JavaScript developers who haven’t heard of them.

This is copied from my comment at https://lobste.rs/s/sz0ltb/float_js_-_introspect_floating-point_numbers_in_js/comments/uvuwfc#c_uvuwfc, so that everyone can see it, not just other Lobsters users.