docs updated

README.md

@@ -20,6 +20,7 @@ By default, configuration lives in `sails.config.babel`.  The configuration key
 Parameter      | Type                | Details
 -------------- | ------------------- |:---------------------------------
 compile        | ((boolean)) | Whether or not sails should compile future JS code.  Defaults to `true`.
+polyfill       | ((boolean)) | Whether or not use `babel-polyfill`.  Defaults to `false`.
 presets        | ((array)) | Which [presets](http://babeljs.io/docs/plugins/#presets) to transpile your code with. Defaults to [es2015](http://babeljs.io/docs/plugins/preset-es2015/).
 ignore         | ((boolean/Regex)) | Can be `false` or a regex of what to ignore. For default mode see http://babeljs.io/docs/usage/require/
 only           | ((Regex)) | Whether or not use babel's [loose](http://babeljs.io/docs/usage/loose/) mode. For default mode see http://babeljs.io/docs/usage/require/