Fix up links between readmes/sub-packages

Author: kevmoo

README.md

@@ -3,24 +3,29 @@
 Provides [source_gen] `Generator`s to create code for JSON serialization and
 deserialization.
 
-## [json_serializable]
+## json_serializable
+
+* Package: https://pub.dartlang.org/packages/json_serializable
+* [Source code](json_serializable)
 
 The core package providing Generators for JSON-specific tasks.
 
 Import it into your pubspec `dev_dependencies:` section.
 
-## [json_annotation]
+## json_annotation
+
+* Package: https://pub.dartlang.org/packages/json_annotation
+* [Source code](json_annotation)
 
 The annotation package which has no dependencies.
 
 Import it into your pubspec `dependencies:` section.
 
-## [example]
+## example
+
+* [Source code](example)
 
-A simple example showing how to setup and use [json_serializable] and
-[json_annotation].
+An example showing how to setup and use `json_serializable` and
+`json_annotation`.
 
-[json_serializable]: https://github.com/dart-lang/json_serializable/blob/master/json_serializable/README.md
-[json_annotation]: https://github.com/dart-lang/json_serializable/blob/master/json_annotation/README.md
-[example]: https://github.com/dart-lang/json_serializable/blob/master/example/README.md
 [source_gen]: https://pub.dartlang.org/packages/source_gen

json_annotation/README.md

@@ -7,6 +7,6 @@ See the [example] to understand how to configure your package.
 
 Please file feature requests and bugs at the [issue tracker][tracker].
 
-[example]: https://github.com/dart-lang/json_serializable/blob/master/example/README.md
+[example]: https://github.com/dart-lang/json_serializable/blob/master/example
 [tracker]: https://github.com/dart-lang/json_serializable/issues
 [json_serializable]: https://pub.dartlang.org/packages/json_serializable

json_serializable/README.md

@@ -81,5 +81,5 @@ abstract class _$PersonSerializerMixin {
 }
 ```
 
-[example]: https://github.com/dart-lang/json_serializable/blob/master/example/README.md
+[example]: https://github.com/dart-lang/json_serializable/blob/master/example
 [source_gen]: https://pub.dartlang.org/packages/source_gen