title: How to bind an <details> element's open attribute in Ember?
body: <p>I have some onboarding steps that are part of a workflow. These steps are contained within a <code>&lt;details&gt;</code> element that I have open by default the first time they visit. To close the details panel, a user can either click a button acknowledging they understand the steps or simply click the <code>&lt;summary&gt;</code> element which is default behaviour for details elements.</p>
  
  <pre><code>&lt;details open={{not isOnboarded}}&gt;
    &lt;summary&gt;Getting Started&lt;/summary&gt;
    &lt;p&gt;some steps about getting started&lt;/p&gt;
  
    &lt;button type="button" {{action 'completeOnboarding'}}&gt;I Understand&lt;/button&gt;
  &lt;/details&gt;
  </code></pre>
  
  <p>Unfortunately, because of the fact that the <code>&lt;details&gt;</code> element toggles the <code>open</code> attribute natively, it seems to be removing Ember's binding.</p>
  
  <p>How can I bind the details opening in Ember?</p>