title: Multiple *ngFor loops in ion-list
body: <p>I have two arrays of data. "subtitles" &amp; "title". How to I properly incorporate the two arrays into an ion-list, so that I have a title and subtitle from the two arrays showing in one ion-item (title on top of the subtitle)?</p>
  
  <p>in my .ts file:</p>
  
  <pre class="lang-ts prettyprint-override"><code>items = [
   'Email',
   'Phone Number',
   'Address',
   'Cards'
  ];
  
  data = [ 
    "first last",
    "test phone number",
    "test address"
  ]
  </code></pre>
  
  <p>in my .html file</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;ion-content padding&gt;
   &lt;ion-list class="list"&gt;
    &lt;div *ngFor="let unit of data"&gt;
      &lt;button ion-item *ngFor="let item of items" (click)="enterPage(item)"&gt;
          {{item}}
          {{unit}}
     &lt;/button&gt;
    &lt;/div&gt;
   &lt;/ion-list&gt;
  &lt;/ion-content&gt;
  </code></pre>