Support for markdown with path depedent uri

[calvinsadewa]

Currently there is already support for autolink markdown file (.md) to generated html documentation page (.html).

However this doesn't extend to path dependent markdown uri, for example ../subscription.md is still rendered as ../subscription.md in generated doc (would like to be subscription.html).

Would it be okay to extend autolinking for markdown to path dependent uri?

here is example taken from Absinthe Guide for ../subscriptions.md

[wojtekmach]

A PR would be very welcome!

[calvinsadewa]

Here is the PR #1187