Update README

Explain that all attributes bindings of Ember.TextField available on the datepicker.

Author: soulim

README.md

@@ -4,6 +4,8 @@ The addon provides you a `bootstrap-datapicker` input component. It can be used
 
 The input component is based on [bootstrap-datepicker library](https://github.com/eternicode/bootstrap-datepicker).
 
+The datepicker input field extends [`Ember.TextField`](http://emberjs.com/api/classes/Ember.TextField.html). That means you have all attribute bindings available on `Ember.TextField`.
+
 ## Installation
 
 ```bash