docs(platform): add telemetry data verification guide

[ArnobKumarSaha]

Summary

• Adds a customer-facing guide for verifying telemetry (logs & metrics) is actually landing in the monitoring stack (ClickHouse for logs, Thanos + S3 for metrics), so customers can self-check their own clusters.
• Includes a troubleshooting section for the common case of metrics being stale due to missing Prometheus remote-write config.

Test plan

• Verified with liche -p -h -l -s — no broken links

[github-actions]

Visit the preview URL for this PR (updated for commit 93dbf26):

https://kubedb-v2-hugo--pr150-arnob-telemetry-chec-2vrk5u7h.web.app

_{(expires Wed, 22 Jul 2026 15:23:34 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: 0f29ae8ae0bd54a99bf2b223b6833be47acd5943}