doc: document go1.6.2

Change-Id: Ib3063719cf90dfad139dd723b3b16ef0b45e312e
Reviewed-on: https://go-review.googlesource.com/22251Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-on: https://go-review.googlesource.com/22253Reviewed-by: Andrew Gerrand <adg@golang.org>

doc/devel/release.html

@@ -45,6 +45,14 @@ See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.6.1">Go
 1.6.1 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.6.2 (released 2016/04/20) includes fixes to the compiler, runtime, tools,
+documentation, and the <code>mime/multipart</code>, <code>net/http</code>, and
+<code>sort</code> packages.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.6.2">Go
+1.6.2 milestone</a> on our issue tracker for details.
+</p>
+
 <h2 id="go1.5">go1.5 (released 2015/08/19)</h2>
 
 <p>