Fix an typo

Author: Xie, Ziyu

src/app/views/adv-demo/iframe-demo/iframe-demo.component.html

@@ -25,7 +25,7 @@ <h6> Draggable & Resizable </h6>
       <tab heading="component">
         <markdown [data]="demo_ts | language: 'typescript'"></markdown>
       </tab>
-      <tab heading="component">
+      <tab heading="scss">
         <markdown [data]="demo_scss | language: 'sass'"></markdown>
       </tab>
     </tabset>