doc: document go1.2.2

R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/100110043

doc/devel/release.html

@@ -27,6 +27,12 @@ go1.2.1 (released 2014/03/02) includes bug fixes to the <code>runtime</code>, <c
 See the <a href="https://code.google.com/p/go/source/list?name=release-branch.go1.2&r=7ada9e760ce34e78aee5b476c9621556d0fa5d31">change history</a> for details.
 </p>
 
+<p>
+go1.2.2 (released 2014/05/05) includes a
+<a href="https://code.google.com/p/go/source/detail?r=bda3619e7a2c&repo=tools">security fix</a>
+that affects the tour binary included in the binary distributions (thanks to Guillaume T).
+</p>
+
 <h2 id="go1.1">go1.1 (released 2013/05/13)</h2>
 
 <p>