Closer Herd integration with Sail/Docker

[vcardillo]

I like Herd so far. However, many production deployment paradigms are based on Docker. Especially if a project needs to take certain compliance into account, it may not be possible to use Forge, for example. In this case, creating a Docker container is ideal. It would be nice if Herd's paradigm worked more transparently with Docker containers, making deployment pipelines from dev to prod easier.