Corrected dead link.

"So I thought that maybe, if I put it up on GitHub, people might want to send me pull requests"
Exactly! :)

Thank you for your writeup. I noticed a dead link, the PDF at:
http://peepcode.com/products/git-internals-pdf
now redirects to
http://www.pluralsight.com/

A quick google located a version on the pluralsight github account:
https://github.com/pluralsight/git-internals-pdf/raw/master/drafts/peepcode-git.pdf

I was about to write you a mail about it, but wait, suggest an update by mail for a text about git? Appreciate that you put it on Github! Here is a pull request for the new link.

:)