End-User Enablement Guide: How to use the `Metrics Operator` within my ControlPlane

Description

The goal of this issue is to write an enablement guide for end-users how they can use a proposed metric tooling to monitor their resources in a ControlPlane.

https://github.com/openmcp-project/backlog/issues/548 evaluated a metric tooling that shall be used within a ControlPlane.

Proposal

Think about how we want to add examples for such metrics in the respective repos to drive end user enablement, see https://github.com/SAP/crossplane-provider-btp/pull/792

Acceptance Criteria

• Enablement guide published unter open-control-plane.io Get stated/end-user section
• End user guide shares commonly used metric examples for reuse
• End user guide demonstrates how to ingest data into any OTEL compatible Data sink [Grafana, Dynatrace, other]
• Proposal how to automatically rotate secrets in the ControlPlane for authentication against OTEL backend

Start with the existing getting-started/end-user section at open-control-plane.io and review backlog issue 548 for the evaluated metric tooling. Use SAP/crossplane-provider-btp pull request 792 as the example reference, then document commonly used metrics, ingestion into an OTEL-compatible sink such as Grafana or Dynatrace, and a proposal for rotating ControlPlane authentication secrets.