Link mimir mixin alerts with their runbook

[angelluismula]

Is your feature request related to a problem? Please describe.

Alerts in /operations/mimir-mixin-compiled/alerts.yaml have not linked with their runbook (https://grafana.com/docs/mimir/next/operators-guide/mimir-runbooks) using annotations.runbook_url or similar

Describe the solution you'd like

Add annotations.runbook_url on each documented alert runbook.

Describe alternatives you've considered

Additional context

I think would be very useful to add runbook url to mimir alerts to use the official guide to resolve it.

[pracucci]

Good point!

At Grafana Labs we use withRunbookURL() from mixin-utils to inject the URL of the published runbook for each Mimir alert.

We could just do the same directly in the Mimir mixin, so that compiled alerts have the runbook URL linked.