Update the pubspec's homepage link.

pkgs/yaml/pubspec.yaml

diff --git a/pkgs/yaml/pubspec.yaml b/pkgs/yaml/pubspec.yaml
index 88650fc..c094c7b 100644
--- a/pkgs/yaml/pubspec.yaml
+++ b/pkgs/yaml/pubspec.yaml
@@ -1,7 +1,7 @@
 name: yaml
 version: 2.1.2
 author: "Dart Team <misc@dartlang.org>"
-homepage: http://www.dartlang.org
+homepage: http://github.com/dart-lang/yaml
 description: A parser for YAML.
 dependencies:
   collection: ">=1.1.0 <2.0.0"