I want to change the base url of my JupyterHub, how can I do this with the Zero to Jupyterhub with Kubernetes project?

I know it is possible to change the hub's base url, it is stated on the bottom of this page: https://jupyterhub.readthedocs.io/en/stable/getting-started/networking-basics.html. But I can't find it as config parameter in the Configuration Reference.