Update tutorial on Prometheus/Grafana

[ktyle]

https://www.zonca.dev/posts/2019-04-20-jetstream_kubernetes_monitoring was last updated in 2020. Could the content be refreshed please?

[zonca]

Prometheus Grafana refresh

[zonca]

@ktyle here it is:

https://www.zonca.dev/posts/2024-10-25-jetstream_kubernetes_grafana

instructions are pretty similar to the old tutorial oddly enough.
But I also found a way to extract Jupyterhub specific metrics, increase retention and attach a PV to prometheus.

Let me know if that works.

[ktyle]

awesome @zonca I will take a look over the next few weeks!