message: docs: fix ngSwitch example
  docs: fix ngSwitch example
  remove the predix "app-" from the confuse emotion ngSwitchCase.
  PR Close
diff: <div [ngSwitch]="hero?.emotion">
  <app-happy-hero *ngSwitchCase="'happy'" [hero]="hero"></app-happy-hero>
  <app-sad-hero *ngSwitchCase="'sad'" [hero]="hero"></app-sad-hero>
  - <app-confused-hero *ngSwitchCase="'app-confused'" [hero]="hero"></app-confused-hero>
  + <app-confused-hero *ngSwitchCase="'confused'" [hero]="hero"></app-confused-hero>
  <app-unknown-hero *ngSwitchDefault [hero]="hero"></app-unknown-hero>
  </div>
  <!-- #enddocregion built-in, ngswitch -->
  