net/url: spell the package name correctly.

R=bradfitz
CC=golang-dev
https://golang.org/cl/5676076
diff --git a/src/pkg/net/url/url.go b/src/pkg/net/url/url.go
index cdfb16c..1d824c0 100644
--- a/src/pkg/net/url/url.go
+++ b/src/pkg/net/url/url.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package URL parses URLs and implements query escaping.
+// Package url parses URLs and implements query escaping.
 // See RFC 3986.
 package url