sysop: Add manual alert creation

docs/sysop.md

@@ -16,6 +16,11 @@ enabled](https://prometheus.io/docs/prometheus/latest/querying/api/#tsdb-admin-a
     :::shell
     curl -u user:pass -X POST -g 'https://prometheus-endpoint/api/v1/admin/tsdb/delete_series?match[]=metric{label="foo"}&start=TIMESTAMP&end=TIMESTAMP
 
+### Add synthetic alert to alertmanager
+
+    :::javascript
+    await fetch("/alertmanager/api/v1/alerts", {method: "POST", body: JSON.stringify([{ "labels": {"alertname": "testalert"}, "annotations": { "description": "manual test alert"}}])})
+
 ## OpenSSL
 
 ### Get certificate expiry date