Product monitoring: Create concepts page

We should document that we recommend a Prometheus Servicemonitor and point to the monitoring stack.
Mention that we label all Services accordingly, so users only need to deploy a Servicemonitor and get all metrics instantly.
Provide some nice screenshots from Prometheus

This is mostly done on https://docs.stackable.tech/home/stable/operators/monitoring/
Expand it with

• some screenshots from Prometheus
• link to the monitoring stack to showcase the setup

從 docs.stackable.tech/home/stable/operators/monitoring/ 現有的 monitoring 頁面開始，檢視目前的指南。補充 Prometheus 截圖、指向 monitoring stack 的連結，以及部署 Prometheus ServiceMonitor 的建議；當設定流程和 metrics 的自動收集獲得清楚說明時，即視為完成。