Merge pull request #1277 from prometheus/beorn7/alerting

Add documentation about alert inhibition

content/docs/alerting/configuration.md

@@ -200,6 +200,12 @@ Semantically, a missing label and a label with an empty value are the same
 thing. Therefore, if all the label names listed in `equal` are missing from
 both the source and target alerts, the inhibition rule will apply.
 
+To prevent an alert from inhibiting itself, an inhibition rule will never
+inhibit an alert that matches _both_ the target and the source side of the
+rule. However, we recommend to choose target and source matchers in a way that
+alerts never match both sides. It is much easier to reason about and does not
+trigger this special case.
+
 ```yaml
 # Matchers that have to be fulfilled in the alerts to be muted.
 target_match: