Small documentation on bisect extension

[David MENTRE]

Hello,

I added a small documentation for the bisect extension on the wiki page,
finding no documentation (albeit the bisect extension being is very
useful):
  http://www.selenic.com/mercurial/wiki/index.cgi/UsingBisect

Feel free to fix/enhance/update.

Best wishes,
d.
-- 
pub  1024D/A3AD7A2A 2004-10-03 David MENTRE <dmentre at linux-france.org>
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