doc: document go1.0.3

R=rsc, r
CC=gobot, golang-dev
https://golang.org/cl/6532049

doc/devel/release.html

@@ -53,6 +53,10 @@ of maps using struct or array keys:
 It also includes many minor code and documentation fixes.
 </p>
 
+<p>
+go1.0.3 (released 2012/09/21) includes minor code and documentation fixes.
+</p>
+
 <p>
 See the <a href="http://code.google.com/p/go/source/list?name=release-branch.go1">go1 release branch history</a> for the complete list of changes.
 </p>