github/git-reference — pull request #47 by randomecho (2012-12-11 22:24:08+00:00)
Title: Drop in two other examples of git reset

Fleshing out what the other two invocations of `git reset` are and bundle them up.

Information based on the following resources mentioned at issue #20:

- http://git-scm.com/2011/07/11/reset.html
- http://www.infoq.com/presentations/A-Tale-of-Three-Trees
- http://schacon.github.com/resetvcheckout.html

Also updates a link to the book no longer at ProGit.org

Hopefully it not only makes sense but it's actually correct.