title: {{content-for 'head'}} Ember-cli
body: <p>I've been using Yeoman ember generator for the past 1 month and now, I'd like to give ember-cli a try.</p>
  
  <p>I run the generator and launch the app, everything works fine. </p>
  
  <pre><code>ember new my-new-app
  ember server
  </code></pre>
  
  <p>but I'd like to know how does </p>
  
  <pre><code>{{content-for 'head'}}
  </code></pre>
  
  <p>in app/index.html works?</p>
  
  <p>When looking at other examples from <a href="http://www.ember-cli.com/#tutorials" rel="noreferrer">http://www.ember-cli.com/#tutorials</a>, none of them are using this particular helper? Is it because they are using older version of ember-cli? Why weren't they using this content-for helper?</p>
  
  <p>I'm pretty sure that ember.js doesn't have this content-for helper in default, so I'm guessing ember-cli wrote it somewhere? Where is it and what is it for? </p>
  
  <p>Also, when I inspect the element of my-new-app page, the div tag of 'Welcome to Ember.js' appeared at the body tag instead of head tag? How is that possible? {{mind-blown}}</p>
  
  <p>( in app/index.html,    {{content-for 'head'}}    is placed inside head tag)</p>