doc: link to go1 and go1compat from docs index

Fixes #3239.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5782049

doc/docs.html

@@ -70,6 +70,19 @@ Answers to common questions about Go.
 <h3 id="wiki"><a href="http://code.google.com/p/go-wiki/wiki">Go Language Community Wiki</a></h3>
 <p>A wiki maintained by the Go community.</p>
 
+<h2 id="go1">Go version 1</h2>
+
+<h3 id="go1notes"><a href="/doc/go1.html">Go 1 Release Notes</a></h3>
+<p>
+A guide for updating your code to work with Go 1.
+</p>
+
+<h3 id="go1compat"><a href="/doc/go1compat.html">Go 1 and the Future of Go Programs</a></h3>
+<p>
+What Go 1 defines and the backwards-compatibility guarantees one can expect as
+Go 1 matures.
+</p>
+
 <h2 id="articles">Go Articles</h2>
 
 <h3 id="blog"><a href="http://blog.golang.org/">The Go Blog</a></h3>