Documentation improvements and minor fixes

- Enhanced README with comprehensive documentation
  - Added supported file types section
  - Documented self-dogfooding feature
  - Added advanced configuration examples
  - Documented all Poupe UI recommended rules
  - Created migration guide from legacy configs
  - Added troubleshooting section
  - Enhanced project structure documentation
- Added meaningful package.json description for npm visibility
- Fixed markdown formatting to comply with 80-char limit

- Removed redundant export from './configs/index' in src/index.ts

- Updated @eslint/js to ^9.30.1
- Updated eslint to ^9.30.1

Full changelog: https://github.com/poupe-ui/eslint-config/compare/v0.7.9...v0.7.10