Default threat_monitoring_alerts feature flag on

- turn threat_monitoring_alerts feature flag on by default
- add information about modifying the feature flag
- add changelog

doc/user/application_security/threat_monitoring/index.md

@@ -187,6 +187,25 @@ a Kubernetes Agent for this project.
 
 ![Policy Editor UI](img/threat_monitoring_add_policy_alert_ui_v13_9.png)
 
+#### Enable or disable Policy Alerts **(FREE SELF)**
+
+Policy Alerts is under development but ready for production use.
+It is deployed behind a feature flag that is **enabled by default**.
+[GitLab administrators with access to the GitLab Rails console](../../../administration/feature_flags.md)
+can opt to disable it.
+
+To enable it:
+
+```ruby
+Feature.enable(:threat_monitoring_alerts)
+```
+
+To disable it:
+
+```ruby
+Feature.disable(:threat_monitoring_alerts)
+```
+
 ### Container Network Policy Alert list
 
 > [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/3438) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 13.9.

ee/app/controllers/projects/threat_monitoring_controller.rb

@@ -7,13 +7,13 @@ module Projects
     before_action :authorize_read_threat_monitoring!
 
     before_action do
-      push_frontend_feature_flag(:threat_monitoring_alerts, project)
+      push_frontend_feature_flag(:threat_monitoring_alerts, project, default_enabled: :yaml)
     end
 
     feature_category :web_firewall
 
     def alert_details
-      render_404 unless Feature.enabled?(:threat_monitoring_alerts, project)
+      render_404 unless Feature.enabled?(:threat_monitoring_alerts, project, default_enabled: :yaml)
       @alert_id = params[:id]
     end
 

ee/changelogs/unreleased/299941-threat-monitoring-alerts-UI-docs.yml

+---
+title: Enable threat_monitoring_alerts feature flag by default
+merge_request: 53776
+author:
+type: added

ee/config/feature_flags/development/threat_monitoring_alerts.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/287676
 milestone: '13.7'
 type: development
 group: group::container security
-default_enabled: false
+default_enabled: true