From-Scratch docker image + Documentation

[Arteneko]

Looking at some old issues (the two that can be found when searching for Dockerfile), it appears that pisa may already have a docker image in some registry.

If so, documentation, or at least a link to this registry's image page, should be added.

If not, it'd be nice to have a from-scratch docker image.

[amallia]

Thank you @IvanDelsinne for opening this issue.
Pisa has a Docker image https://github.com/pisa-engine/docker, which still need to be improved.
Currently the binaries are built when the Docker image is built. It would be nice to build the binaries in the machine where the Docker is running, because otherwise the binaries are not optimized for the architecture.

In the meantime, do you want to open a PR for the documentation?