docs(guide/component): remove redundant empty controller from example

There is no need for empty controller functions on components, since this is the
default.

Closes #16003

Author: sercaneraslan

docs/content/guide/component.ngdoc

@@ -39,14 +39,8 @@ Components can be registered using the `.component()` method of an AngularJS mod
   });
 </file>
 <file name="heroDetail.js">
-
-  function HeroDetailController() {
-
-  }
-
   angular.module('heroApp').component('heroDetail', {
     templateUrl: 'heroDetail.html',
-    controller: HeroDetailController,
     bindings: {
       hero: '='
     }