title: how to restrict checkbox selection up to 3 in angular 7
body: <p>in angular how to restrict checkbox selection up to 3</p>
  
  <pre><code>&lt;ion-item *ngFor="let check of checks;"&gt;
     &lt;ion-label&gt;{check.name}}&lt;/ion-label&gt;
     &lt;ion-checkbox slot="start" [value]="check.value" (click)="selectChecked()"&gt;
  &lt;/ion-checkbox&gt;&lt;/ion-item&gt;
  
  checks = [{name: "item 1"},.... ]
  </code></pre>