doc/go1.1: fix metadata json format

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6570054

doc/go1.1.html

 <!--{
 	"Title": "Go 1.1 Release Notes",
-	"Path":  "/doc/go1.1"
+	"Path":  "/doc/go1.1",
 	"Template": true
 }-->