feat(user-notify): add link to SES reputation metrics dashboard

docs/services/user-notify.md

@@ -31,6 +31,11 @@ The deployment is configured in the following repositories
 * [GKE-hosted GitLab CI
   runners](https://gitlab.developers.cam.ac.uk/uis/devops/devhub/gitlab-runner-infrastructure/-/blob/master/locals.tf?ref_type=heads)
 
+## Dashboards
+
+Reputation metrics for SES-originated email can be seen in a [dedicated
+dashboard](https://console.cloud.google.com/monitoring/dashboards/builder/9ad42d9f-f591-4495-a035-830c3f6ba13c;duration=P14D?project=user-notify-prod-68cf8181).
+
 ## Operational documentation
 
 [Operational documentation](https://uis.uniofcam.dev/devops/user-notify/infrastructure) is currently