http://wiki.x.org/wiki/Development/git updated

[Jesse Barnes]

I found myself pointing people at krh's blog post on building the stack a lot 
recently, so I figured it should be made into an x.org wiki page.  We already 
had a git development guide started, so I updated it based on krh's guide and 
a couple of the replies in his blog.

Please give it a try and update it as needed (it could use a little 
beautifying, for example adding links for the various sections), and is 
missing proto & library build info, as well as a Gallium build guide, but it 
should be useful as-is...

Jesse