Render Scribble like
@hyperlink["url" "content"]
as Markdown like
[content](url)
Note that this only works for `@hyperlink`. The motivation is to
preserve content the author has explicitly written. (Previously,
`markdown-render.rkt` was discarding this; `text-render.rkt` still
does so.)
This does _not_ attempt to handle everything that `html-render.rkt`
would automatically generate and render as `<a>`. It simply can't --
things like hotlinked Racket keywords in code blocks simply won't work
in Markdown.
original commit: dbffc840a93ceb142c59df4a533ced0b41b8e4fa
Uses "Github flavored markdown". Specifically, code blocks are opened
using ```scheme so that Github will lex and format them as Scheme code
rather than generic monospace.
Note: I would have used ```racket, but we are still waiting for the
pygments.rb project to pull again from pygments-main -- to which I
contributed a Racket lexer back in August. After pygments.rb pulls,
can update this to use ```racket instead.
original commit: 6aa6dc0400f4fed688e6f5b5278da2e34d82ad88
