Remove reference to internal

- The self-monitoring project can be connected to any Prometheus
instance. Make this more clear in the docs.

doc/administration/monitoring/gitlab_instance_administration_project/index.md

+# GitLab instance administration project
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/56883) in GitLab 12.2.
+
+GitLab has been adding the ability for administrators to see insights into the health of
+their GitLab instance. In order to surface this experience in a native way, similar to how
+you would interact with an application deployed via GitLab, a base project called
+"GitLab Instance Administration" with
+[internal visibility](../../../public_access/public_access.md#internal-projects) will be
+added under a group called "GitLab Instance Administrators" specifically created for
+visualizing and configuring the monitoring of your GitLab instance.
+
+All administrators at the time of creation of the project and group will be added
+as maintainers of the group and project, and as an admin, you'll be able to add new
+members to the group in order to give them maintainer access to the project.
+
+This project will be used for self-monitoring your GitLab instance.
+
+## Connection to Prometheus
+
+The project will be automatically configured to connect to the
+[internal Prometheus](../prometheus/index.md) instance if the Prometheus
+instance is present (should be the case if GitLab was installed via Omnibus
+and you haven't disabled it).
+
+If that's not the case or if you have an external Prometheus instance or an HA setup,
+you should
+[configure it manually](../../../user/project/integrations/prometheus.md#manual-configuration-of-prometheus).
+
+## Taking action on Prometheus alerts **[ULTIMATE]**
+
+You can [add a webhook](../../../user/project/integrations/prometheus.md#external-prometheus-instances)
+to the Prometheus config in order for GitLab to receive notifications of any alerts.
+
+Once the webhook is setup, you can
+[take action on incoming alerts](../../../user/project/integrations/prometheus.md#taking-action-on-incidents-ultimate).

doc/administration/monitoring/index.md

@@ -2,6 +2,9 @@
 
 Explore our features to monitor your GitLab instance:
 
+- [GitLab self-monitoring](gitlab_instance_administration_project/index.md): The
+  GitLab instance administration project helps to monitor the GitLab instance and
+  take action on alerts.
 - [Performance monitoring](performance/index.md): GitLab Performance Monitoring makes it possible to measure a wide variety of statistics of your instance.
 - [Prometheus](prometheus/index.md): Prometheus is a powerful time-series monitoring service, providing a flexible platform for monitoring GitLab and other software products.
 - [GitHub imports](github_imports.md): Monitor the health and progress of GitLab's GitHub importer with various Prometheus metrics.