Update lib documentation

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

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

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

No files or tests are named. Start by locating the handler implementation, serialization path, and configuration parsing, then determine how a new enable_serialization option should flow through them. Done means handlers can be serialized for production deployments while the option defaults to false.

Written by the indexing model from the issue text.