docs: quick start revision

- [ ] add the description about real-time data import
- [ ] consider changing the offline data import as the soft copy approach
- [ ] update English doc as well

Find the quick start documentation in the repository, likely under docs/ or a similar directory. Review the current sections on data import, distinguishing between real-time and offline methods. Update the English documentation to clarify real-time data import and reframe offline import as a soft copy approach. Ensure changes are consistent across any translated versions.

索引モデルが issue の本文から書いたものです。