docs(readme): filled README

README.md

@@ -1,2 +1,51 @@
-# express-json-error-handler
+# express-json-error-handler [![Build Status](https://travis-ci.org/noamokman/express-json-error-handler.svg?branch=master)](https://travis-ci.org/noamokman/express-json-error-handler) [![Coverage Status](https://coveralls.io/repos/github/noamokman/express-json-error-handler/badge.svg?branch=master)](https://coveralls.io/github/noamokman/express-json-error-handler?branch=master)
+
 Error handler for express JSON APIs
+
+
+## Installation
+``` bash
+$ [sudo] npm install express-json-error-handler --save
+```
+
+## Usage
+
+### Example
+``` js
+import express from 'express';
+import jsonErrorHandler from 'express-json-error-handler';
+
+const app = express();
+
+app.use(jsonErrorHandler());
+
+```
+
+## Options
+
+The `jsonErrorHandler` function takes an option `options` object that may contain any of
+the following keys:
+
+### log
+
+The `log` option, if supplied, is called as `log({err, req, res})` when server errors occur.
+#### Example
+``` js
+import express from 'express';
+import jsonErrorHandler from 'express-json-error-handler';
+
+const app = express();
+
+app.use(jsonErrorHandler({
+  log({err, req, res}) {
+    console.log(err); // The original error object
+    console.log(req); // The request object
+    console.log(res); // The response object
+  }
+}));
+
+```
+
+## License
+
+[MIT](LICENSE)