Add shared volume from Jupyterhub container TO notebook container

I’m running GitHub - jupyterhub/jupyterhub-deploy-docker: Reference deployment of JupyterHub with docker on a VM. I correctly set up everything, but now I need the spawned notebook to contain a shared folder with some data that I have on the VM.

I edited the docker-compose file in order to have the “shared” folder initially on the VM also present on the JupyterHub container, adding the last line in this snippet:

      # Bind Docker socket on the host so we can connect to the daemon from
      # within the container
      - "/var/run/docker.sock:/var/run/docker.sock:rw"
      # Bind Docker volume on host for JupyterHub database and cookie secrets
      - "data:${DATA_VOLUME_CONTAINER}"
      #Add a "shared" folder on the VM to the JupyterHub container
      - "./shared:/shared"

But then I don’t know how to link that folder to the notebook. I tried with
c.DockerSpawner.volumes = { 'jupyterhub-user-{username}': notebook_dir, '/shared': {"bind": '/home/jovyan/work/shared', "mode": "ro"}}
inside the, but nothing happens.
Any suggestions?