Add documentation, Github Action for Dockerfile

[BSchilperoort]

PR #214 adds a dockerfile. No documentation for users on how to run this (instead of the executable directly) is available yet.

We will have to document:

• How to build the image locally
• How to run the image and mount directories

Additionally, a Github Action can be set up that will build and publish a new version of the docker image when a release is made on this repository. This will make it easier and less work to keep the Docker image in sync with the code.

[BSchilperoort]

The Docker image is now automagically built and pushed when a release is made