more updates for README

Author: zhengbli

README.md

@@ -17,8 +17,10 @@ files used for Visual Studio JavaScript language service;
 
 ## Input Files:
 - `browser.webidl.xml`: the XML spec file generated by Microsoft Edge (due to the different updating schedules between Edge and TypeScript, this may **not** be the most up-to-date version of the spec.);
-- `addedTypes.json`: types should exist in either browser or webworker that are missing from the Edge spec. The type can be `property`, `method`, `interface`, `constructor`, or `indexer`.
+- `webworker.webidl.xml`: contains additional types for webworker.
+- `addedTypes.json`: types that should exist in either browser or webworker but are missing from the Edge spec. The type can be `property`, `method`, `interface`, `constructor`, or `indexer`.
 - `overridingTypes.json`: types that are defined in the spec file but has a better or more up-to-date definitions in the json files.
 - `removedTypes.json`: types that are defined in the spec file but should be removed.
-- `comments.json`: 
+- `comments.json`: comment strings to be embedded in the generated .js files
 - `jsTemplate.js`: the initial templates for `domWeb.js` and `domWindows.js`, which contains the necessary helper functions;
+- `sample.json`: sample json file used to tell F# json type provider that structure of the json files. The content of it is not used anywhere.