[DOCS] Add `NoRepeatNGramLogitsProcessor` Example for `LogitsProcessor` class
# What does this PR do?

This PR adds an example to the docstring of `NoRepeatNGramLogitsProcessor` and edits the docstring description of the same.
This is with reference to #24783 and is part of the #24575 

Fixes # (issue)
#24783

## 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?
- [x] 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).


## Who can review?

@gante @sgugger 

### Additional Notes:

In comparison with [TFNoRepeatNGramLogitsProcessor](https://github.com/huggingface/transformers/blob/05cda5df3405e6a2ee4ecf8f7e1b2300ebda472e/src/transformers/generation/tf_logits_process.py#L388), I noticed that the required functions `_get_ngrams`, `_get_generated_ngrams`, and `_calc_banned_ngram_tokens` were outside the class. Is this expected?


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_25186). All of your documentation changes will be reflected on that endpoint.<|||||>Hey @gante Thanks for your feedback. I've made the requested changes. Let me know what you think. <|||||>@gante I've made the recommended changes. Does this look better?