doc/go1: fix broken link

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/5695072

doc/go1.html

@@ -1786,7 +1786,7 @@ The compiler will catch code using the old interface.
 The <a href="/pkg/regexp/"><code>regexp</code></a> package has been rewritten.
 It has the same interface but the specification of the regular expressions 
 it supports has changed from the old "egrep" form to that of
-<a href="code.google.com/p/re2">RE2</a>.
+<a href="http://code.google.com/p/re2/">RE2</a>.
 </p>
 
 <p>

doc/go1.tmpl

@@ -1671,7 +1671,7 @@ The compiler will catch code using the old interface.
 The <a href="/pkg/regexp/"><code>regexp</code></a> package has been rewritten.
 It has the same interface but the specification of the regular expressions 
 it supports has changed from the old "egrep" form to that of
-<a href="code.google.com/p/re2">RE2</a>.
+<a href="http://code.google.com/p/re2/">RE2</a>.
 </p>
 
 <p>