The new group will be useful to add yet another section about how to
manage silences.

Using the filter bar for creating alerts can help us create more
advanced filters more easily.

service/prometheus.md

@@ -106,7 +106,18 @@ any particular outage. If it's not present, it's a bug and can be filed as such.
 [`prometheus-alerts.git` repository]: https://gitlab.torproject.org/tpo/tpa/prometheus-alerts
 [rules configuration dump]: https://prometheus.torproject.org/classic/rules
 
-## Silencing an alert in advance
+## Silencing alerts
+
+With Alertmanager, you can stop alerts from sending notifications by creating a
+"silence". A silence is an expression matching alerts with tags and other
+values with a start and end times. Silences can have optional author name and
+description, and we strongly recommend setting them so that others can refer to
+you if they have questions.
+
+The main method for managing silences is via the [Karma dashboard][]. You can
+also manage them on the command line via fabric.
+
+### Silencing an alert in advance
 
 Say you are planning some service maintenance and expect an alert to
 trigger, but you don't want things to be screaming everywhere.
@@ -141,7 +152,7 @@ checkbox and a UUID, which is the unique identifier for this alert, as
 a link to the Alertmanager. Don't click that link, as it doesn't work
 and anyways we can do everything we do with alerts in Karma.
 
-## Silencing active alerts
+### Silencing active alerts
 
 Silencing active alerts is slightly easier than planning one in
 advance. You can just:
@@ -159,6 +170,13 @@ checkbox and a UUID, which is the unique identifier for this alert, as
 a link to the Alertmanager. Don't click that link, as it doesn't work
 and anyways we can do everything we do with alerts in Karma.
 
+Note that you can replace steps 2 and 3 above with a series of manipulations to
+get a filter in the top bar that corresponds to what you want to silence (for
+example clicking on a label in alerts, or manually entering new filtering
+criteria) and then clicking on the bell icon at the top, just right of the
+filter bar. This method can help you create a silence for more than just one
+alert at a time.
+
 ## Adding metrics to applications
 
 If you want your service to be monitored by Prometheus, you need to