Deprecate alerts for Managed Prometheus

changelogs/unreleased/deprecate_alerts_managed_prometheus.yml

+---
+title: Deprecate Alerts for Managed Prometheus
+merge_request: 59433
+author:
+type: deprecated

doc/operations/metrics/alerts.md

@@ -17,6 +17,10 @@ your team when environment performance falls outside of the boundaries you set.
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/6590) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 11.2 for [custom metrics](index.md#adding-custom-metrics), and GitLab 11.3 for [library metrics](../../user/project/integrations/prometheus_library/index.md).
 
+WARNING:
+Managed Prometheus on Kubernetes is [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/327796)
+and scheduled for [removal in GitLab 14.0](https://gitlab.com/groups/gitlab-org/-/epics/4280).
+
 For managed Prometheus instances using auto configuration, you can
 [configure alerts for metrics](index.md#adding-custom-metrics) directly in the
 [metrics dashboard](index.md). To set an alert: