Update config documentation

**Problem**
When working with validation, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

The issue does not name any files, tests, or entry points. First locate the configuration documentation and the validation error-handling code, then determine whether the requested work is documentation-only or also changes runtime behavior. Done means the scope is resolved, validation failures have detailed messages, and the related configuration documentation reflects the final behavior.

Written by the indexing model from the issue text.