vendor: fix vendor.json

Missing a level of nesting.

Change-Id: I1dbe87bf00d5bbc9c17b514f85a6ee3bf75f1160
Reviewed-on: https://go-review.googlesource.com/14022
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 8936735..dc333c0 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -1,8 +1,10 @@
 {
 	"package": [
-		"canonical": "rsc.io/pdf",
-		"local": "rsc.io/pdf",
-		"revision": "371ad118eb63f9f52971201c4e903420401ed37f",
-		"revisionTime": "2015-07-23T06:11:39Z"
+		{
+			"canonical": "rsc.io/pdf",
+			"local": "rsc.io/pdf",
+			"revision": "371ad118eb63f9f52971201c4e903420401ed37f",
+			"revisionTime": "2015-07-23T06:11:39Z"
+		}
 	]
 }