title: Update Rxjs observable of array by adding ,filtering or deleting items
body: <p>I have some cards displayed in the UI.</p>
  <pre><code>&lt;div *ngFor=&quot;let item of cards | async&quot;&gt;...&lt;/div&gt;
  </code></pre>
  <p>Obviosuly cards will be the Observable of array of type card.</p>
  <p>So I have an interface of card lets say it has 3 properties</p>
  <p>Id, name, description.</p>
  <p>My use case is.</p>
  <ol>
  <li><p>I want to add new card to the observables array and must reflect to array.</p>
  </li>
  <li><p>I want to delete the card from the observable and must reflect to the template.</p>
  </li>
  <li><p>I must be able to filter the card baaed on lets say name and must be reflected in the template.</p>
  </li>
  </ol>
  <p>In short all the aperations must be done in the observable as I have used async pipe in the template.</p>