AWS prescriptive-guidance documentation change
Summary
Renamed file from welcome.md to introduction.md and updated content: removed publication date/document history, added overview of hexagonal architecture benefits, updated AWS reference format, and fixed broken link.
Security assessment
Changes focus on architectural concepts (hexagonal patterns, DDD) and development practices (SOLID principles, test-driven development). No security vulnerabilities, security features, or security-related terminology are mentioned. Updates are purely about software design methodology.