doc: fix anchor ID in weekly.html.

R=adg, rsc
CC=golang-dev
https://golang.org/cl/5359055

doc/devel/weekly.html

@@ -14,7 +14,7 @@ hg pull
 hg update weekly.<i>YYYY-MM-DD</i>
 </pre>
 
-<h2 id="2011-11-08">2011-11-09</h2>
+<h2 id="2011-11-09">2011-11-09</h2>
 
 <pre>
 This weekly snapshot renames various Go packages as described in the Go 1 plan.