Useful to have docker instructions in README.md?

I have Haskell already installed on my system, and that includes `stack` but not `cabal`.
So, in order to run the tests for this course, I installed `ghcup` in Docker, then cabal, and ran the tests there.

Would a PR with instructions for how to do this be useful? Or a `Dockerfile` even?

Start by reviewing README.md and the Docker-based ghcup and cabal setup described in the issue. Decide whether README instructions, a Dockerfile, or both are in scope, then verify that the documented setup supports running the course tests.

Written by the indexing model from the issue text.