Fixes#7407
Add comprehensive documentation and example configuration for using
nginx as a reverse proxy with SeaweedFS S3 API while maintaining AWS
Signature V4 authentication compatibility.
Changes:
- Add docker/nginx/README.md with detailed setup guide
- Add docker/nginx/s3-example.conf with working configuration
- Update docker/nginx/proxy.conf with important S3 notes
The documentation covers:
- Critical requirements for AWS Signature V4 authentication
- Common mistakes and why they break S3 authentication
- Complete working nginx configurations
- Debugging tips and troubleshooting
- Performance tuning recommendations
