Autodiscovery of git repositories from HTML

I have a web page which lives in a git repository so that it can be easily mirrored. I would like to use a "rel" link to the URL of the git repository so that it can be automatically discovered, like an RSS feed:

<link rel="alternate" type="???" href="http://example.com/.git"/>

Is there any existing convention as to what the type should be? Note that this isn't necessarily the same question as what a git repository should be served as over HTTP: the Universal Edit Button uses a dummy MIME type of "application/x-wiki".

Thomas