pdf cleanup: fix links, remove internal references.

fix link in spec.

R=rsc
CC=go-dev
http://go/go-review/1017013

doc/go_spec.html

@@ -21,7 +21,7 @@ Todo
 
 <p>
 This is a reference manual for the Go programming language. For
-more information and other documents, see <a href="http://go/go">go/go</a>.
+more information and other documents, see <a href="http://golang.org/">http://golang.org</a>.
 </p>
 
 <p>