message: added ion-backdrop component to UI component sidebar
diff: @@ -89,7 +89,8 @@ const items = {
  },
  'Modal': {
  'ion-modal': '/docs/api/modal',
  - 'ion-modal-controller': '/docs/api/modal-controller'
  + 'ion-modal-controller': '/docs/api/modal-controller',
  + 'ion-backdrop': '/docs/api/backdrop'
  },
  'Navigation': {
  'ion-nav': '/docs/api/nav',
  