🌐 [i18n-KO] Translated `training.mdx` to Korean
# What does this PR do?

Translated the `training.mdx` file of the documentation to Korean.
Thank you in advance for your review. 

Part of https://github.com/huggingface/transformers/issues/20179

## Before submitting
- [x] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [ ] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [x] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [ ] 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

 May you please review this PR?
@sgugger, @ArthurZucker, @eunseojo

<!-- @sgugger, @ArthurZucker, @eunseojo May you please review this PR? -->
<!-- Team PseudoLab, may you please review this PR?
@0525hhgus, @KIHOON71, @sim-so, @gabrielwithappy, @HanNayeoniee, @wonhyeongseo, @jungnerd -->
_The documentation is not available anymore as the PR was closed or merged._<|||||>Team PseudoLab, may you please review this PR?
@0525hhgus, @KIHOON71, @sim-so, @gabrielwithappy, @HanNayeoniee, @wonhyeongseo, @jungnerd
- fixed some ambiguous translations of the autoclass_tutorial doc. 
(from https://github.com/huggingface/transformers/pull/22533)
- translated training doc.<|||||>fixed review comments :-) 
Thank you your kind reivews.
BRs
@HanNayeoniee @sim-so @wonhyeongseo <|||||>May you please review this PR?
@sgugger, @ArthurZucker, @eunseojo