title: is there an option to change icon for completed step in material-2 stepper
body: <p>Currently the icon for completed step is 'create'. How can I change it to some other material icon line, like 'Done' ?</p>
  
  <pre><code>&lt;mat-vertical-stepper&gt;
      &lt;mat-step label="Agreement Preparation"&gt;
          &lt;p&gt;Agreement preparion is intiated by our side &lt;/p&gt;
      &lt;/mat-step&gt;
      &lt;mat-step label="Ready for Biometric"&gt;
          &lt;p&gt;Agreement preparion is intiated by our side &lt;/p&gt;
  
      &lt;/mat-step&gt;
      &lt;mat-step label="Document in Submission"&gt;
          &lt;p&gt;Agreement preparion is intiated by our side &lt;/p&gt;
  
      &lt;/mat-step&gt;
  &lt;/mat-vertical-stepper&gt;
  </code></pre>