[Docs] Clarify Subphrase classification?
Author: hamelsmu
Pull request: no

I am going through the docs linearly and am reading [Summary of The tasks](https://huggingface.co/transformers/task_summary.html).

The second section of [Sequence Classification](https://huggingface.co/transformers/task_summary.html) uses `bert-base-cased-finetuned-mrpc` to do paraphrase classification.  

This is a bit opaque to me, as when I go to the [model page](https://huggingface.co/bert-base-cased-finetuned-mrpc) for that particular model, it doesn't really mention this capability?

How could I discover other models that have this capability?  How do I verify what this model was fine-tuned on if I was searching for this information from the model hub?  Is there some other documentation about this that I am missing? 

Just trying to understand so I can help clarify the docs.  Thanks!

@sgugger 

Comments:
The problem lies mostly on the model page in that case, it should show the text classification widget, not the masked LM widget. As for adding a model card or expanding its capabilities, the feedback should go on the [forums](https://discuss.huggingface.co/), this is not really an issue with transformers per se.

This is a great example of where pull requests on the model hub would be useful! (cc @julien-c )

Ok thanks I'll close this issue and open an appropriate PR/Issue in other places.  I'll try to find where to update the filter and I'll put the model card on my todo list.  

Thanks for the pointers

For anyone that finds this issue:

 - [here is the forum post that describes how to suggest model cards](https://discuss.huggingface.co/t/about-the-model-cards-category/2777)

- For clarification `bert-base-cased-finetuned-mrpc` does indeed do masked LM but it additionally also does text classification (I tried doing both).  But, it looks like models on the hub can only associated with one widget at a time?  so It could be the case that models have hidden functionality, or does this particular model violate some kind of norm?  

- @hamelsmu The model card for this model should a minima reference the `mrpc` dataset, though we don't have it as a standalone dataset so the way to go would be to link to `glue` instead. (right @lhoestq?)
- you can also add a `tags: - paraphrase-classification ` to the YAML (tags are pretty much open)
- read the doc about the model hub here http://huggingface.co/docs (should it be linked more prominently from the transformers doc?)
- As this is a "legacy" model (not inside an organization), it's hard to remember who trained it and therefore could answer more questions (the original BERT authors? Someone from HF?)
- To your last question, most models only have one head so one task – for simplicity we enforce this constraint of only having one widget or Inference API endpoint per model

Yes for now we have to link to `glue`.
Though I've noticed that many models use the `mrpc` tag that doesn't link to glue

Maybe we can define a syntax that mentions both glue (to link to the glue dataset page) and MRPC (to mention which config if the glue dataset was used). Maybe `glue/mrpc` or `glue:mrpc`. Shall I open an issue on the website repo about this @julien-c ?