Ionic 4: How to hide label in Tabbar?

I want to create only icon based tabbar.
I did as I told in the document but I couldnt’ get the results I wanted.
How I hide label in the tabbar in Ionic 4.

<ion-tabs tabbarLayout="label-hide">
  <ion-tab label="about" icon="about" href="/tabs/(about:about)">
    <ion-router-outlet name="about"></ion-router-outlet>
  </ion-tab>
</ion-tabs>