[Feature Request] Alerts does not have description

[zhenyatsk]

Hello.

First of all Thank you for brining us such great project.

It would be great if an ability to set Alerts description would exist. For now alerts does not have descriptions.

[7840vz]

For now you can add description as kubernetes annotations in SLO CR:

metadata:
  annotations:
    pyrra.dev/description: "This is an alert description in ErrorBudgetBurn and SLOAbsent alerts"
    pyrra.dev/summary: "This is an alert summary in ErrorBudgetBurn and SLOAbsent alerts"