Add reference to Git::Hooks

Hello Matthew.

I hope this is the proper way to suggest an addition to your githooks.com site. If not, please, let me know how do you prefer to get it.

I'm suggesting a link to a project of mine, called [Git::Hooks](https://github.com/gnustavo/Git-Hooks). It's a framework for simplifying the implementation and usage of Git hooks.

I hope it's not too much self-serving of my part. :-)

BTW, it seems that your site (githooks.com) isn't uptodate with regards to the contents of the gh-pages branch.

Regards.

--
Gustavo.