Update README.md

[toncho11]

Updated how to use the docker file.

[gcattan]

Nice! Thank you @toncho11

Additionally, we could also push the docker image to the github repository:
https://github.com/pyRiemann/pyRiemann-qiskit/blob/main/.github/workflows/create_docker_image.yml

[toncho11]

So what is the difference with https://github.com/pyRiemann/pyRiemann-qiskit/blob/main/Dockerfile ?

[gcattan]

The command you added to the readme is building the image in your local, and starts a container based on this image.
We could do the same on each release, and make the image available on GitHub. Then one can connect to the repo (docker login...) and download the docker image directly (without building it locally) (docker pull...).
The workflow I linked is the one we use to build the docker image for each PR. The two lines commented at the end push the image to the docker registry of this GitHub repo.
An improvement could be to listen not only for PRs, but also for release events, and enables the two last lines when it is a release.