Fix config option to disable Prometheus

doc/administration/monitoring/prometheus/index.md

@@ -35,10 +35,10 @@ monitoring target for Prometheus, unless individually disabled.
 To disable Prometheus and all of its exporters, as well as any added in the future:
 1. Edit `/etc/gitlab/gitlab.rb`
-1. Add or find and uncomment the following line, making sure it's set to `true`:
+1. Add or find and uncomment the following line, making sure it's set to `false`:
     ```ruby
-    prometheus['disable_all'] = true
+    prometheus_monitoring['enable'] = false
     ```
 1. Save the file and [reconfigure GitLab][reconfigure] for the changes to

doc/install/requirements.md

@@ -162,4 +162,4 @@ about it, check the [Prometheus documentation](../administration/monitoring/prom
 We support the current and the previous major release of Firefox, Chrome/Chromium, Safari and Microsoft browsers (Microsoft Edge and Internet Explorer 11).
-Each time a new browser version is released, we begin supporting that version and stop supporting the third most recent version.
+Each time a new browser version is released, we begin supporting that version and stop supporting the third most recent version.
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