* docs(ko): proofread chapter_hello_algo introduction
Proofread the Korean translation of chapter_hello_algo/index.md.
Improve unnatural phrasing, grammar, and readability while preserving the original meaning and analogies.
* docs(ko): address review feedback on introduction
Address the reviewer's feedback:
- Restore the original "knowledge map" metaphor.
- Use consistent Korean reader address and refine the wording for readability.
- Preserve line alignment with the Chinese source.