Setting up ruler with loki-stack

[Korijn]

I've recently upgraded our loki-stack deployment from about a year ago to the current latest version of the chart (v2.8.2), and sadly the alerts that I had configured in my dashboards no longer work. Apparently the whole alerting system has been revamped, but I can't seem to find any clear instructions or examples of how to configure the helm chart to get the new alerting system enabled. I just see errors on the Alerts page in Grafana that the Ruler API is not detected:

It's totally unclear to me what to do about this.

Any tips? Configuration examples for values.yaml would be super useful.