title: adding directive to a angular 2 component
body: <p>I recently created a simple project using angular 2. When I try to add a directive component to the app.component, there's a red underline for 'directives' property. 
  Anybody tell me what's wrong here?</p>
  
  <p><a href="https://i.stack.imgur.com/j5vo5.png" rel="noreferrer"><img src="https://i.stack.imgur.com/j5vo5.png" alt="enter image description here"></a></p>