Document CAKE traffic shaping integration - Resolves issue #77

[amirhmoradi]

Added comprehensive documentation for the existing CAKE traffic shaping support in traffic-weir module. CAKE (Common Applications Kept Enhanced) is already fully implemented in the Go-based traffic-weir module with HTB and HFSC scheduler support.

Changes:

• Created docs/TRAFFIC_SHAPING.md: Complete guide covering all three schedulers (CAKE, HTB, HFSC) with performance comparisons, use cases, configuration examples, and troubleshooting

• Updated README.md: Added "Key Features" section highlighting CAKE with quick start example and traffic shaping overview

• Created docs/examples/traffic_shaping_examples.md: Practical API examples including real-world scenarios (multi-tier VPN, office departments, family VPN), batch operations with Python/Bash scripts, and comprehensive error handling

• Enhanced Docs/API_DOCUMENTATION.md: Expanded Traffic Weir API section with detailed scheduler comparison table, performance benchmarks, selection guide, and important notes about scheduler locking

Key highlights:

• CAKE is recommended for modern deployments (gaming, VoIP, mixed traffic)
• Automatic bufferbloat mitigation keeps latency under 20ms under load
• Per-flow NAT-aware fairness prevents bandwidth monopolization
• HTB for legacy systems and simple rate limiting
• HFSC for guaranteed bandwidth SLA requirements

Implementation already exists in:

• Src/traffic_weir/scheduler/cake.go
• Src/traffic_weir/tests/cake_test.go
• Src/wiregate/routes/traffic_weir_api.py (API integration)

This PR addresses issue #77 by documenting the existing CAKE implementation rather than adding redundant Python scripts.