delete jupyterhub

I removed jupyerhub module as it is not an IDE but a scalable way using K8s to host JupyterLab for teams.  We can do https://tljh.jupyter.org/en/latest/install/custom-server.html, which also fits an example template. Alternatively, we can do the legacy https://jupyter-notebook.readthedocs.io/en/stable/.

jupyterhub/README.md

@@ -1,16 +0,0 @@
----
-display_name: JupyterHub
-description: A multi-user version of the notebook designed for companies, classrooms and research labs
-icon: ../.icons/jupyter.svg
-maintainer_github: coder
-verified: true
-tags: [helper, ide, web, jupyter]
----
-
-# JupyterHub
-
-Automatically install [JupyterHub](https://jupyter.org/hub) in a workspace, and create an app to access it via the dashboard.
-
-## Examples
-
-TODO