Swag example: Update doc format
# What does this PR do?

Updates the doc format in the swag examples (requested [here](https://github.com/huggingface/transformers/pull/15868#discussion_r816869590))
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_16014). All of your documentation changes will be reflected on that endpoint.