Github markdown fragments

Github markdown output where headings had slugified fragment links, but the corresponding id-attribute had a user-content- string prepended, which github then handles with javascript, are now retried by hyperlink to see if this special case is true.

example:

<a id="user-content-6-test262-status" class="anchor" aria-hidden="true" href="#6-test262-status">

Hyperlink will no longer report these fragments as broken if the content is hosted on github.com