monitoring: Update Mikrotik exporter

monitoring/README.md

@@ -55,7 +55,14 @@ To set Mikrotik secrets:
 
 ```
  kubectl create -n monitoring secret generic mikrotik-exporter \
-  --from-literal=MIKROTIK_PASSWORD='f7W!H*Pu' \
-  --from-literal=PROMETHEUS_BEARER_TOKEN=$(cat /dev/urandom | base64 | head -c 30)
+  --from-literal=username=netpoller \
+  --from-literal=password=...
 ```
 
+To wipe timeseries:
+
+```
+for replica in $(seq 0 2); do
+  kubectl exec -n monitoring prometheus-prometheus-$replica -- wget --post-data='match[]={__name__=~"mikrotik_.*"}' http://127.0.0.1:9090/api/v1/admin/tsdb/delete_series -O -
+done
+```