Add missing information on token_type_ids for roberta model
# What does this PR do?

Add missing information on token_type_ids for roberta model

Fixes #19744

- [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?

## Who can review?

@sgugger 
_The documentation is not available anymore as the PR was closed or merged._<|||||>> Thanks for the PR. Can you be a bit more explicit as the configuration will always be initialized with this parameter. Maybe it needs to be 2 for instance? Or any vlaue >= 2?

Done