minor model card description updates
# What does this PR do?

Makes a few minor updates to the [joeddav/xlm-roberta-large-xnli](https://huggingface.co/joeddav/xlm-roberta-large-xnli) model card, such as removing the reference to the deprecated zero shot demo when the user can play with zero shot classification via the embedded widget. Also links to distilled bart models.