docs(readme): fix caching layer attribution in architecture description

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: nanotaboada

README.md

@@ -147,7 +147,7 @@ graph RL
 
 **Composition Root Pattern:** The `main` module acts as the composition root, creating the FastAPI app and registering all routers. This pattern enables dependency injection via `Depends()`, improves testability, and maintains clear separation of concerns.
 
-**Layered Architecture:** HTTP requests flow through distinct layers: `routes` → `services` → `schemas` → `databases`. Each layer has a specific responsibility — routes handle HTTP mapping and validation, services contain business logic and caching, schemas define the ORM model, and databases manage the async session.
+**Layered Architecture:** HTTP requests flow through distinct layers: `routes` → `services` → `schemas` → `databases`. Each layer has a specific responsibility — routes handle HTTP mapping, validation, and in-memory caching, services contain business logic, schemas define the ORM model, and databases manage the async session.
 
 **Color Coding:** Core packages (blue) implement the application logic, external dependencies (red) are third-party frameworks and ORMs, and tests (green) ensure code quality.