Update docs/source/ko/_toctree.yml

[jungnerd]

What does this PR do?

Updated the outdated docs/source/ko/_toctree.yml and reorganized the file locations accordingly.

Part of #20179

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Who can review?

Hi @stevhliu 👋
I modified docs/source/ko/_toctree.yml because the table of contents of the Korean documentation was outdated.
May you please review this PR?

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[stevhliu]

Thanks for updating! Would you mind resolving the conflict and then I can merge :)