Merge pull request #48 from videojs/readmecredentials

add section in README re:withCredentials

@@ -49,6 +49,24 @@ support for:
 - Segment codecs _other than_ H.264 with AAC audio
 - Internet Explorer < 10
 
+### Plugin Options
+
+You may pass in an options object to the hls plugin upon initialization. This
+object may contain one of the following properties:
+
+#### withCredentials
+Type: `boolean`
+
+When the `withCredentials` property is set to `true`, all XHR requests for
+manifests and segments would have `withCredentials` set to `true` as well. This
+enables storing and passing cookies from the server that the manifests and
+segments live on. This has some implications on CORS because when set, the
+`Access-Control-Allow-Origin` header cannot be set to `*`, also, the response
+headers require the addition of `Access-Control-Allow-Credentials` header which
+is set to `true`.
+See [html5rocks's article](http://www.html5rocks.com/en/tutorials/cors/)
+for more info
+
 ### Runtime Properties
 #### player.hls.master
 Type: `object`