I think it would be good to expand on what happens outside of `docker build` time to make sure there's no ambiguity for our more creative readers :)

What dastardly things happen if I `BINDCONTXT /etc`, - I presume that allows me to feel safe that the final image will have a clean /etc just like the FROM container had.

if I `BINDCONTEXT /non-existant-dir` will that dir exist in the final image, but be empty?

fun feature.