Add runbook links to notifications

[dafydd-t]

We have notifications for failed bench tests for PDC, but the messages aren't immediately actionable for those who are on-call and who are not familiar with PDC's test suite (so nearly everyone who's on call for it 😅 )

Our notifications look like this:

I'd love to be able to add a runbook link to this notification, like we can add dashboard links (example)

[jalevin]

@dafydd-t Hey! thank you for reporting this issue and apologies for not seeing it sooner. Would you be up for taking a stab at adding support for this with your favorite LLM of choice? I think it would be pretty straight forward.