Move documentation to MkDocs and add comprehensive guides

Reorganized documentation to be part of MkDocs site with three new
comprehensive guides covering API7 Gateway configuration.

Changes:

1. Documentation Structure:
   - Moved SECRET-MANAGEMENT.md from helm/ to web/docs/
   - Created service-discovery.md with complete guide
   - Created ingress-routing.md with routing architecture
   - Moved externalsecret examples to web/docs/examples/

2. New Documentation - Service Discovery:
   - How service discovery works (architecture diagram)
   - Benefits vs static configuration
   - Configuration examples
   - RBAC requirements
   - Advanced use cases (auto-scaling, rolling updates)
   - Load balancing algorithms
   - Monitoring and troubleshooting
   - Best practices

3. New Documentation - Ingress & Routing:
   - Complete traffic flow architecture
   - Ingress configuration explained
   - Gateway routing rules and priority
   - URI matching patterns (prefix, exact, regex)
   - TLS/SSL with cert-manager
   - Advanced routing scenarios:
     * Multiple domains
     * Path-based routing
     * Header-based routing
     * Method-based routing
   - Configuration examples (microservices, WebSocket, canary)
   - Monitoring and debugging
   - Troubleshooting common issues

4. MkDocs Navigation:
   - Updated mkdocs.yml with new pages in Configuration section
   - Added: Ingress & Routing
   - Added: Service Discovery
   - Added: Secret Management

5. Examples Directory:
   - Created web/docs/examples/ for configuration examples
   - Moved ExternalSecret examples with multiple providers:
     * AWS Secrets Manager
     * HashiCorp Vault
     * Azure Key Vault
     * GCP Secret Manager

All documentation now integrated into MkDocs site with proper
navigation, cross-references, and Material theme styling.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

web/mkdocs.yml

@@ -41,6 +41,9 @@ nav:
       - Kubernetes Resources: kubernetes-resources.md
   - Configuration:
       - API7 Gateway: api7-configuration.md
+      - Ingress & Routing: ingress-routing.md
+      - Service Discovery: service-discovery.md
+      - Secret Management: secret-management.md
       - CI/CD Pipeline: cicd-pipeline.md
   - Troubleshooting: troubleshooting.md