Update routes documentation

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

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

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

Start by locating the routes documentation and the configuration entry point for the proposed `enable_export` option. Clarify what validation export should produce and verify that the option defaults to `false`; the documentation and an appropriate validation check should reflect the agreed behavior.

Written by the indexing model from the issue text.