Update middleware documentation

**Feature request**
It would be great to have filtering for api.

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

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

Start by locating the middleware configuration entry point and the existing API request path; the issue names no file or test. Done means the new enable_filtering option defaults to false and filtering works for the API without changing the default behavior.

Written by the indexing model from the issue text.