[release-branch.go1.5] doc: correct release date for go1.5.2

Change-Id: I6bee207db7485f96a499f51b2d1346c35e086d41
Reviewed-on: https://go-review.googlesource.com/17337Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-on: https://go-review.googlesource.com/17338Reviewed-by: Chris Broadfoot <cbro@golang.org>

doc/devel/release.html

@@ -22,7 +22,7 @@ Read the <a href="/doc/go1.5">Go 1.5 Release Notes</a> for more information.
 <h3 id="go1.5.minor">Minor revisions</h3>
 
 <p>
-go1.5.2 (released 2015/11/23) includes bug fixes to the compiler, linker, and
+go1.5.2 (released 2015/12/02) includes bug fixes to the compiler, linker, and
 the <code>mime/multipart</code>, <code>net</code>, and <code>runtime</code>
 packages.
 See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.5.2">Go