docs(demos): remove attr from docs

demos/attr/index.ts

@@ -1,17 +0,0 @@
-import {App} from 'ionic/ionic';
-
-@App({
-  templateUrl: 'main.html'
-})
-
-class DemoApp {
-
-  constructor() {
-    this.isHidden = false;
-  }
-
-  toggle() {
-    this.isHidden = !this.isHidden;
-  }
-
-}

demos/attr/main.html

@@ -1,30 +0,0 @@
-
-<ion-toolbar>
-  <ion-title>attr</ion-title>
-</ion-toolbar>
-
-<ion-content padding style="text-align:center">
-
-
-
-  <ion-row>
-    <ion-col>
-      <b>[attr.hidden]="isHidden ? '' : null"</b>
-    </ion-col>
-  </ion-row>
-
-  <ion-row>
-    <ion-col>
-      <b>isHidden:</b> {{isHidden}}
-    </ion-col>
-  </ion-row>
-
-  <ion-row>
-    <ion-col>
-      <ion-icon name="ionic" [attr.hidden]="isHidden ? '' : null" style="font-size: 52px; text-align: center;"></ion-icon>
-    </ion-col>
-  </ion-row>
-
-  <button (click)="toggle()">Toggle Icon</button>
-
-</ion-content>

ionic/components/app/id.ts

@@ -66,15 +66,7 @@ export class IdRef {
 
 
 /**
- * @name Attr
- * @description
- * Attr allows you to dynamically add or remove an attribute based on the value of an expression or variable.
- * @usage
- * ```html
- * // toggle the no-lines attributes based on whether isAndroid is true or false
- * <ion-list [attr.no-lines]="isAndroid ? '' : null">
- * ```
- * @demo /docs/v2/demos/attr/
+ * @private
  */
 @Directive({
   selector: '[attr]'