Add complete documentation in French including:
- Table of contents for easy navigation
- Prerequisites section (0k dev-pack, Docker, rsync, sudo)
- Project structure explanation with directory tree
- Detailed workflow explanation with step-by-step breakdown
- ASCII diagram showing migration flow
- Usage examples with command-line syntax
- Customization guide for version-specific scripts
- Troubleshooting section with common issues and solutions
Replace the previous minimal README that only contained basic
installation and configuration notes.
