title: Get user info with userId - Angular Firestore
body: <p>I've got 2 different collections:</p>
  
  <ul>
  <li>Users: name, email and avatar (taken from their social network)</li>
  <li>Recipes: documents that the user can create. It also contains <code>userId</code> with their references to previous collection</li>
  </ul>
  
  <p>To display these recipes on my page I use:</p>
  
  <pre><code>this.recipes = collection.snapshotChanges().map(actions =&gt; {
        return actions.map(action =&gt; ({
          $id: action.payload.doc.id,
          ...action.payload.doc.data()
        }));
      });
  </code></pre>
  
  <p>And:</p>
  
  <pre><code>&lt;ion-card *ngFor="let recipe of recipes | async; let i = index"&gt;
  ...
  </code></pre>
  
  <p>What's the best way to get also the user avatar and name? </p>