Documentation: add "Fighting regressions with git bisect" article

Documentation: add "Fighting regressions with git bisect" article

This patch adds an asciidoc version of the "Fighting regressions with
git bisect" article that the author wrote for the Linux-Kongress
2009 (http://www.linux-kongress.org/2009).

This paper might be interesting to people who want to learn as much as
possible about "git bisect" from a single document.

The slides of the related presentation are available at:

http://www.linux-kongress.org/2009/slides/fighting_regressions_with_git_bisect_christian_couder.pdf

But the Linux Kongress people will not publish this paper online because
they print the papers on their UpTimes magazine
(http://www.lob.de/isbn/978-3-86541-358-1). But they don't take away the
rights of the author (which is very nice), so I have the right to publish
it.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>