Update doc/feature_001.md with more info on the technical specifications

doc/feature_001.md

@@ -118,4 +118,15 @@
 - When David accepts the invitation
 - Then he becomes a member of the salon
 - When David declines the invitation
-- Then Bob is notified of the refusal
+- Then Bob is notified of the refusal
+
+
+
+# Technical specifications
+
+- **.NET**: Main framework for backend, API, and business logic.
+- **Angular**: Framework used for developing the interactive web frontend.
+- **Docker**: Containerization of services to facilitate deployment and portability.
+- **Logto**: Authentication and identity management solution to secure access.
+- **SQLite**: Lightweight database, ideal for local storage or testing environments.
+- **Hetzner**: Hosting provider for production deployment (servers, cloud).