Update auth documentation

**Feature request**
It would be great to have caching for store.

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

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

Start by locating the store implementation and configuration handling, then determine how authentication-related store data is currently accessed. Clarify the caching scope, invalidation behavior, and production requirements before changing anything. Done should include the enable_caching option defaulting to false and verified caching behavior, but the issue does not name tests or files.

Written by the indexing model from the issue text.