[WIP] 🌐 [i18n-KO] Translated sequence_classification.mdx to Korean

[0525hhgus]

What does this PR do?

Translated the tasks/sequence_classification.mdx file of the documentation to Korean.

• The file name is sequence_classification.mdx, but the document name is text classification.

Thank you in advance for your review:)

Part of #20179

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

Team PseudoLab, may you please review this PR?

@0525hhgus, @kihoon71, @sim-so, @gabrielwithappy, @HanNayeoniee, @wonhyeongseo, @jungnerd

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[0525hhgus]

There is a problem with the storage stream, so I will PR it again.. 😢