title: :as in rails routes.rb
body: <p>In <code>config/routes.rb</code>, I tried both:</p>
  
  <pre><code>root :to =&gt; 'things#index', :as =&gt; 'things'
  </code></pre>
  
  <p>and</p>
  
  <pre><code>root :to =&gt; 'things#index'
  </code></pre>
  
  <p>When I hit <code>http://localhost:3000/</code>, both approaches work, and nothing seems to be different.</p>
  
  <p>What is the <code>:as</code> option used for?</p>