[v2] Document how to control internal observability

* How to enable debug logging in the storage
* How to control & export tracing
* How to read and control metrics
* Health checks + config https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/extension/healthcheckv2extension/README.md#v2

Some/most of these settings are in the OTEL config.

Start with the linked healthcheckv2extension README and inspect the repository's existing OTEL configuration documentation. Identify where storage debug logging, tracing export and control, metrics, and health-check configuration are currently described. Done means the documentation covers each listed control and explains how to read or configure it.

Written by the indexing model from the issue text.