doc: update links in FAQ

Vitess and protobuf has moved to GitHub; update the links.

Change-Id: I2d90bde1a7f2b590c8b7b08ce73d6faa13b51da0
Reviewed-on: https://go-review.googlesource.com/2166Reviewed-by: Andrew Gerrand <adg@golang.org>

doc/go_faq.html

@@ -228,7 +228,7 @@ document server running in a production configuration on
 </p>
 
 <p>
-Other examples include the <a href="//code.google.com/p/vitess/">Vitess</a>
+Other examples include the <a href="//github.com/youtube/vitess/">Vitess</a>
 system for large-scale SQL installations and Google's download server, <code>dl.google.com</code>,
 which delivers Chrome binaries and other large installables such as <code>apt-get</code>
 packages.
@@ -260,7 +260,7 @@ Does Go support Google's protocol buffers?</h3>
 <p>
 A separate open source project provides the necessary compiler plugin and library.
 It is available at
-<a href="//code.google.com/p/goprotobuf/">code.google.com/p/goprotobuf/</a>
+<a href="//github.com/golang/protobuf">github.com/golang/protobuf/</a>
 </p>