Automatically build Docker images for docker-compose-web using GitHub Actions

[007-mark]

It would be nice if we could automatically pull and update to the latest docker image from e.g. docker hub instead of having to build and maintain it manually from github. The requirement to build the binaries for docker is a big hurdle to overcome for many people. #76

https://medium.com/@kicsipixel/using-github-actions-to-automatically-build-docker-images-65a038b8ce56