prometheus-operator: Fix Alertmanager integration

prometheus-operator/README.md

@@ -9,7 +9,16 @@ kubectl create -n prometheus-operator configmap snmp-exporter --from-file=snmp.y
 kubectl apply -n prometheus-operator -f application.yml -f node-exporter.yml -f blackbox-exporter.yml -f snmp-exporter.yml -f mikrotik-exporter.yml
 ```
 
-# Mikrotik expoeter
+
+# Slack
+
+```
+ kubectl create -n prometheus-operator secret generic slack-secrets \
+    --from-literal=webhook-url=https://hooks.slack.com/services/...
+```
+
+
+# Mikrotik exporter
 
 ```
  kubectl create -n prometheus-operator secret generic mikrotik-exporter \