Support rendering markdown "alerts" syntax

[magurotuna]

It would be great if we could add support for rendering "alerts" syntax that's available recently in GitHub: https://github.com/orgs/community/discussions/16925

An example that uses this syntax is @badrap/valita. As shown in the screenshot below, this syntax is rendered with no decoration, which is okay but not ideal.

To support this syntax, we need to fix markdown parsing logic performed in the backend API server, which intenally calls deno_doc::html::jsdoc::markdown_to_html, and finally ending up with comrak crate as a markdown parser library. The problem is that this crate doesn't plan to support "alerts" syntax at least for the time being (see kivikakk/comrak#352). We need to come up with another solution here.

[crowlKats]

Closing as this was implemented