Apply Markdown processing to ALL instances of descriptions

[skyzyx]

I make heavy use of Markdown in my GraphQL documentation. Some tools get this right, while others have odd gaps in support. For example, even GraphiQL leaves some Markdown unprocessed.

It would be nice if all descriptions were processed with Markdown to generate HTML. If HTML output isn't appropriate, then do Markdown → HTML generation, followed by stripping HTML tags from the output.

This would provide a cleaner experience with the text.

[seanb4t]

Of note, graphql spec expects documentation to be rendered with CommonMark.

https://graphql.github.io/graphql-spec/June2018/#sec-Documentation