add pyenv kernel inside jupyterhub

linux/workstation/python.markdown

@@ -40,3 +40,14 @@ pip list --local
 ```
 
 There is currently only one installation inside `/opt/software/pyenv/`, but we will probably add different versions in the future. Although this is similar in spirit to what is done on [Euler HPC](https://scicomp.ethz.ch/wiki/Python_on_Euler_(Ubuntu)), we may not completely freeze all package versions but potentially update some packages in-place. So consider working with dedicated venvs if your projects are very sensitive to package versions.
+
+### Configuring pyenv as additional kernel in JupyterHub
+
+If you are using a locally installed JupyterHub, you can add the pyenv Python as separate iPython kernel.
+
+```sh
+source /opt/software/pyenv/env/default
+ipython kernel install --name "opt-software-pyenv" --user
+```
+
+This creates a custom configuration `~/.local/share/jupyter/kernels/opt-software-pyenv/kernel.json` in your home. Inside JupyterHub you should now be able to pick this kernel in the `Kernel -> Change kernel` menu.