Generate OpenAPI doc using better tool.

[jortel]

Problem

The current tool for generating docs crashes and can't followed aliases or nested types very well.
Also, the syntax adds a lot of clutter.

Let's consider:

go-swagger:

Links:

• https://goswagger.io/use/spec.html
• https://www.mitrais.com/news-updates/implementing-golang-api-documentation-using-go-swagger/

[mansam]

Improvements to documentation generation were made in #545, including automatic conversion of our Swagger 2 documentation to OpenAPI3.0.