Add redirect and renaming note for exporter

doc/administration/monitoring/prometheus/gitlab_exporter.md

 # GitLab exporter
 
->**Note:**
-Available since [Omnibus GitLab 8.17][1132]. For installations from source
-you'll have to install and configure it yourself.
+>- Available since [Omnibus GitLab 8.17](https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1132).
+>- Renamed from `GitLab monitor exporter` to `GitLab exporter` in [GitLab 12.3](https://gitlab.com/gitlab-org/gitlab/merge_requests/16511).
 
-The [GitLab exporter] allows you to measure various GitLab metrics, pulled from Redis and the database.
+The [GitLab exporter](https://gitlab.com/gitlab-org/gitlab-exporter) allows you to
+measure various GitLab metrics, pulled from Redis and the database, in Omnibus GitLab
+instances.
 
-To enable the GitLab exporter:
+NOTE: **Note:**
+For installations from source you'll have to install and configure it yourself.
+
+To enable the GitLab exporter in an Omnibus GitLab instance:
 
 1. [Enable Prometheus](index.md#configuring-prometheus)
 1. Edit `/etc/gitlab/gitlab.rb`
@@ -16,15 +20,10 @@ To enable the GitLab exporter:
    gitlab_exporter['enable'] = true
    ```
 
-1. Save the file and [reconfigure GitLab][reconfigure] for the changes to
-   take effect
+1. Save the file and [reconfigure GitLab](../../restart_gitlab.md#omnibus-gitlab-reconfigure)
+   for the changes to take effect
 
 Prometheus will now automatically begin collecting performance data from
 the GitLab exporter exposed under `localhost:9168`.
 
 [← Back to the main Prometheus page](index.md)
-
-[1132]: https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1132
-[GitLab exporter]: https://gitlab.com/gitlab-org/gitlab-exporter
-[prometheus]: https://prometheus.io
-[reconfigure]: ../../restart_gitlab.md#omnibus-gitlab-reconfigure

doc/administration/monitoring/prometheus/gitlab_monitor_exporter.md

+---
+redirect_to: 'gitlab_exporter.md'
+---
+
+This document was moved to [another location](gitlab_exporter.md).