Relative to absolute links in markdown output

[JosXa]

Hi Kenneth,

I was just referred to this lib and I must say it's just as awesome as everything for Humans 👍

Since we already have the capability to transform relative links to absolute ones according to the readme, would it be possible to swap out all of the relative links in the generated markdown of an element to absolute ones aswell (this would be a sensible default)?

Cheers

[kennethreitz]

removed markdown output, for now.