Update core documentation

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

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

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

No files or tests are named. Start by tracing the existing validation and configuration handling, then determine what filtering should include and where enable_filtering belongs. Done means the behavior is specified, the option defaults to false, and coverage verifies the filtering configuration.

Written by the indexing model from the issue text.