Update validation documentation

**Feature request**
It would be great to have retry for config.

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

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

Start by locating the configuration handling and validation entry points for the terminal agent; the issue does not name specific files or tests. Trace how production configuration is loaded, then verify that enable_retry defaults to false and that enabling it provides the requested retry behavior.

Written by the indexing model from the issue text.