Add "Download OpenAPI spec" link

[elisherer]

Can we make such a download file button/link?

I know the yaml file is in the assets and creating a "file" pointing to it does work, but it doesn't show on the markdown file in GitHub (so it can't be updated programatically)
i.e.
{% download path=".gitbook/assets/openapi.yaml" %} Download OpenAPI spec {% enddownload %}