What documentation would you like to be added:
Karmada metrics documentation improvement.

Why do you think this document is needed:
Now, the related documents(https://karmada.io/docs/next/reference/instrumentation/metrics/#metrics) is too simple, users don't know:

• Are these metrics in the stable version, will these metrics be deprecated?
• How to query these metrics and what do these metrics look like? Give some demos.
• These metrics should be grouped by components.

referring to:

• https://kubernetes.io/docs/reference/instrumentation/metrics/
• https://kubernetes.io/docs/concepts/cluster-administration/system-metrics/

Where do you think the document should be placed:

https://github.com/karmada-io/website/tree/main/docs/reference/instrumentation/metrics.md