Update config documentation

**Feature request**
It would be great to have encryption for handlers.

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

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

Start by locating the configuration definitions and handler setup, then compare how existing boolean options are documented and tested. Confirm the intended encryption behavior for handlers, add the option with a default of false, and update the relevant configuration documentation; the issue names no files or tests.

Written by the indexing model from the issue text.