Added it documentation for fast_tokenizers #17459
# What does this PR do?


Addresses #17459 with italian translation of fast_tokenizers.mdx


## 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).
- [ ] Did you write any new necessary tests?



The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_17622). All of your documentation changes will be reflected on that endpoint.<|||||>Hi @andreafailla, I'm just taking a look at your PR. Can I ask you to change a little of thing? In the toctree please remove the quotation marks here "Usare i tokenizzatori di 🤗 Tokenizers". Everything else looks perfect to me! <|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.