docs(demos): add tabs demo with scenarios

references driftyco/ionic-site#397

ionic/components/tabs/tab.ts

@@ -76,6 +76,7 @@ import {TabButton} from './tab-button';
  * @property {String} [tabBadgeStyle] - set the badge color for this tab
  * @property {Any} (select) - method to call when the current tab is selected
  *
+ * @demo /docs/v2/demos/tabs/ 
  */
 @Component({
   selector: 'ion-tab',

ionic/components/tabs/tabs.ts

@@ -36,6 +36,7 @@ import {isUndefined, isTrueProperty} from '../../util/util';
  * individual Tab components. On iOS, the TabBar is placed on the bottom of
  * the screen, while on Android it is at the top.
  *
+ * @demo /docs/v2/demos/tabs/
  * @see {@link /docs/v2/components#tabs Tabs Component Docs}
  * @see {@link ../Tab Tab API Docs}
  */