Leveling Up - Build products and caching

file to edit: https://github.com/haskell/cabal-userguide/blob/main/src/leveling_up/04_build_products_and_caching.md

## Brief Summary

The motivation for this chapter is to reveal some of the internals of cabal. It shouldn't be a deep dive, but an explanation of where things end up, and some performance considerations that will be useful! It might be a good idea to cover manually busting the cache, and clearing out build artefacts, as well as best practices.

## Resources

[Old cabal user guide build products](https://cabal.readthedocs.io/en/3.4/nix-local-build.html#where-are-my-build-products)
[Old cabal user guide caching](https://cabal.readthedocs.io/en/3.4/nix-local-build.html#caching)