Comprehensive documentation overhaul for Charon features:
Rewrite features.md as marketing overview (87% reduction)
Create comprehensive dns-challenge.md for new DNS feature
Expand 18 feature stub pages into complete documentation:
SSL certificates, CrowdSec, WAF, ACLs, rate limiting
Security headers, proxy headers, web UI, Docker integration
Caddyfile import, logs, WebSocket, backup/restore
Live reload, localization, API, UI themes, supply chain security
Update README.md with DNS Challenge in Top Features
Total: ~2,000+ lines of new user-facing documentation
Refs: #21, #461
Complete documentation overhaul for DNS Challenge Support feature (PR #461):
Rewrite features.md as marketing overview (87% reduction: 1,952 → 249 lines)
Organize features into 8 logical categories with "Learn More" links
Add comprehensive dns-challenge.md with:
15+ supported DNS providers (Cloudflare, Route53, DigitalOcean, etc.)
Step-by-step setup guides
Provider-specific configuration
Manual DNS challenge workflow
Troubleshooting section
Create 18 feature documentation stub pages
Update README.md with DNS Challenge in Top Features section
Refs: #21, #461
