[i18n]Translated "attention.mdx" to korean (#23878)

* [i18n]Translated "attention.mdx" to korean

Co-Authored-By: Hyeonseo Yun <0525yhs@gmail.com>
Co-Authored-By: Wonhyeong Seo <wonhseo@kakao.com>
Co-Authored-By: Sohyun Sim <96299403+sim-so@users.noreply.github.com>
Co-Authored-By: Gabriel Yang <gabrielwithhappy@gmail.com>
Co-Authored-By: Nayeon Han <nayeon2.han@gmail.com>
Co-Authored-By: Jungnerd <46880056+jungnerd@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Sohyun Sim <96299403+sim-so@users.noreply.github.com>
Co-authored-by: Hyeonseo Yun <0525yhs@gmail.com>

* Update _toctree.yml

---------

Co-authored-by: Hyeonseo Yun <0525yhs@gmail.com>
Co-authored-by: Wonhyeong Seo <wonhseo@kakao.com>
Co-authored-by: Sohyun Sim <96299403+sim-so@users.noreply.github.com>
Co-authored-by: Gabriel Yang <gabrielwithhappy@gmail.com>
Co-authored-by: Nayeon Han <nayeon2.han@gmail.com>
Co-authored-by: Jungnerd <46880056+jungnerd@users.noreply.github.com>

docs/source/ko/_toctree.yml

@@ -164,8 +164,8 @@
     title: (번역중) The Transformer model family
   - local: in_translation
     title: (번역중) Summary of the tokenizers
-  - local: in_translation
-    title: (번역중) Attention mechanisms
+  - local: attention
+    title: 어텐션 매커니즘
   - local: pad_truncation
     title: 패딩과 잘라내기
   - local: bertology
@@ -673,4 +673,4 @@
     - local: in_translation
       title: (번역중) Utilities for Time Series
     title: (번역중) Internal Helpers
-  title: (번역중) API
+  title: (번역중) API