add homepage & environment

pubspec.yaml

@@ -2,6 +2,9 @@ name: webfeed
 version: 0.1.0
 description: A dart package for parsing web feed.
 author: Wito Chandra <wito.c.91@gmail.com>
+homepage: https://github.com/witochandra/webfeed
+environment:
+  sdk: ">=1.8.0 <2.0.0"
 dependencies:
   xml: "^3.0.0"
 dev_dependencies: