doc: remove Go for C++ Programmers

Now available at the Go Wiki:
http://code.google.com/p/go-wiki/wiki/GoForCPPProgrammers

Fixes #2913.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5705049

doc/docs.html

@@ -60,7 +60,6 @@ Answers to common questions about Go.
 <ul>
 <li><a href="/doc/articles/wiki/">Writing Web Applications</a> - 
 	building a simple web application.</li>
-<li><a href="go_for_cpp_programmers.html">Go for C++ Programmers</a></li>
 </ul>
 
 <h2 id="articles">Go Articles</h2>