🌐 [i18n-KO] Translated `perf_train_gpu_many.md` to Korean (#26244)

* dos: ko: perf_train_gpu_many.mdx

* feat: chatgpt draft

* fix: manual edits

* fix: resolve suggestions

Change description
Follow the glossary
Fix discrepancies
Co-Authored-By: SeongWooChoi <46990061+nuatmochoi@users.noreply.github.com>
Co-Authored-By: 이서정 <97655267+sjlee-wise@users.noreply.github.com>
Co-Authored-By: Steven Liu <59462357+stevhliu@users.noreply.github.com>

---------
Co-authored-by: Hyunho <105839613+hyunhp@users.noreply.github.com>
Co-authored-by: SeongWooChoi <46990061+nuatmochoi@users.noreply.github.com>
Co-authored-by: 이서정 <97655267+sjlee-wise@users.noreply.github.com>
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

docs/source/ko/_toctree.yml

@@ -117,8 +117,8 @@
       title: 성능 및 확장성
     - local: in_translation
       title: (번역중) Training on one GPU
-    - local: in_translation
-      title: (번역중) Training on many GPUs
+    - local: perf_train_gpu_many
+      title: 다중 GPU에서 훈련 진행하기
     - local: perf_train_cpu
       title: CPU에서 훈련
     - local: perf_train_cpu_many