[i18n-KO] Translated quicktour page to Korean (#20946)

docs: ko: quicktour page

review by @ArthurZucker
docs: fix: remove duplicate
Co-Authored-By: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

docs/source/ko/_toctree.yml

 - sections:
   - local: index
     title: 🤗 Transformers
+  - local: quicktour
+    title: 둘러보기
   - local: installation
     title: 설치방법
   title: 시작하기