🌐 [i18n-KO] Fixed `tasks/masked_language_modeling.mdx`
# What does this PR do?

Fixes #22838

![image](https://user-images.githubusercontent.com/33839093/234049816-7c69151b-e2d1-4018-9a3c-bf9778723f68.png)



## 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
_The documentation is not available anymore as the PR was closed or merged._<|||||>LGTM. If you may, please:

- **amend your commit message to be more descriptive than just `fixed`.**
  (e.g. `fix: docs: missing newline before code block`)
- (Optional) provide relevant screenshots of your fixes<|||||>> LGTM. If you may, please:
> 
> * **amend your commit message to be more descriptive than just `fixed`.**
>   (e.g. `fix: docs: missing newline before code block`)
> * (Optional) provide relevant screenshots of your fixes

Thanks for your review!
I amended the last commit message and added a screenshot in my first comment!