update preface

Author: schacon

book/preface.asc

@@ -32,3 +32,9 @@ I didn't much like that I was writing what I felt was essentially a community re
 While I still don't love that conflict of interests, the importance of GitHub in the Git community is unavoidable.
 Instead of an example of Git hosting, I have decided to turn that part of the book into more deeply describing what GitHub is and how to effectively use it.
 If you are going to learn how to use Git then knowing how to use GitHub will help you take part in a huge community, which is valuable no matter which Git host you decide to use for your own code.
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+The other large change in the time since the last publishing has been the development and rise of the HTTP protocol for Git network transactions. Most of the examples in the book have been changed to HTTP from SSH because it's so much simpler.
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+It's been amazing to watch Git grow over the past few years from a relatively obscure version control system to basically dominating commercial and open source version control. I'm happy that Pro Git has done so well and has also been able to be one of the few technical books on the market that is both quite successful and fully open source.
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+I hope you enjoy this updated edition of Pro Git.