Merge pull request #1864 from darkbaby123/patch-1

Fix ion-nav-back-button document

Author: mhartington

Diff for: js/angular/directive/navBackButton.js

@@ -29,7 +29,7 @@
  * ```html
  * <ion-nav-bar ng-controller="MyCtrl">
  *   <ion-nav-back-button class="button-clear"
- *     ng-click="doSomethingCool()">
+ *     ng-click="goBack()">
  *     <i class="ion-arrow-left-c"></i> Back
  *   </ion-nav-back-button>
  * </ion-nav-bar>