title: Swift version & update Swift version
body: <p>I'm using <code>swift</code> script in my terminal and it shows </p>
  
  <blockquote>
    <p>Welcome to Swift version 1.2. Type :help for assistance.</p>
  </blockquote>
  
  <p>Is it the right way to show Swift's version？</p>
  
  <p>And how to update Swift's version to 2.0?</p>