doc: remove link to PackageVersioning wiki

That page may be fine for experienced Go programmers
but it's not really targeting new programmers.
There's too much we don't know yet.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/14345043

doc/go_faq.html

@@ -1060,11 +1060,6 @@ For example, you might copy "original.com/pkg" to "you.com/external/original.com
 Keith Rarick's <a href="https://github.com/kr/goven">goven</a> is one tool to help automate this process.
 </p>
 
-<p>
-The <a href="/wiki/PackageVersioning">PackageVersioning</a> wiki page collects 
-additional tools and approaches.
-</p>
-
 <h2 id="Pointers">Pointers and Allocation</h2>
 
 <h3 id="pass_by_value">