Update middleware documentation

**Feature request**
It would be great to have export for parsers.

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

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

No file or test is named. Start by locating the middleware configuration and parser handling, then determine how an `enable_export` option with a default of `false` should control parser exports. Done means the option and requested export behavior are implemented and covered by appropriate tests.

Written by the indexing model from the issue text.