Update middleware documentation

**Feature request**
It would be great to have monitoring for middleware.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_monitoring` with default `false`.

Start by locating the middleware configuration and monitoring entry points in the Operator repository. Determine what production monitoring should report and how the new option is expected to behave; done means middleware monitoring is available when enable_monitoring is true and remains disabled by default.

Written by the indexing model from the issue text.