Installation documentation improvement about installing in jupyterhub and/or jupyter server environment

[dirkdaems]

While reading the documentation, it is not clear to me whether this extension needs to be installed on the Jupyterhub only. I can imagine that the extension also needs to be installed in the JupyterLab Docker container that is being spawned (using k8s, Docker Swarm, ...) as the repository needs to become available in that environment? Can this be clarified?