docs(demos): fix item sliding demo and add the slides demo to the slide doc

references ionic-team/ionic-site#397

Author: brandyscarney

demos/item-sliding/main.html

@@ -41,7 +41,7 @@ <h2>Cher</h2>
           <img src="./avatar-dionne.png">
         </ion-avatar>
         <h2>Dionne</h2>
-        <p>Mr. Hall was way harsh on my report card.</p>
+        <p>Mr. Hall was way harsh.</p>
         <ion-note item-right>
           8:59 pm
         </ion-note>

ionic/components/slides/slides.ts

@@ -689,6 +689,7 @@ export class Slides extends Ion {
   * @description
   * `ion-slide` is a child component of `ion-slides` and is where all your individule slide content will be rendered too.
   *
+  * @demo /docs/v2/demos/slides/
   * @see {@link /docs/v2/api/components/slides/Slides/ Slides API Docs}
   */
 @Component({