title: When child array updates UI does not refresh in knockout js
body: <p>I am working on knockout js. I have an observable array object like</p>
  
  <p>viewModel () {</p>
  
  <pre><code>self.myObservableArray = ko.observableArray();
  
  
  }
  </code></pre>
  
  <p>After some asyc api call, I will update the array like this</p>
  
  <pre><code>self.myObservableArray().push({
      "name" : "Some name",
      "childArray" : []
  });
  </code></pre>
  
  <p>After second aync api call, I will have to loop through the response and push an item inside childArray in each loop. </p>
  
  <pre><code>self.myObservableArray()[0]. childArray.push({
          "childName" : "name " + $index
      })
  </code></pre>
  
  <p>But UI does not refresh as I updating second level array. What is the correct way to add elements so UI refreshes or atleast is there a way to trigger the event that says parent property is changed. </p>