title: Exposing a Specific Action of a Nested Route
body: <p>Using this as an example contexted:
  Post has_many comments
  Comment belongs_to post</p>
  
  <p>I have a route that looks like:</p>
  
  <pre><code>resources :posts do
    resources :comments
  end
  </code></pre>
  
  <p>How do i create a route that exposes comments#index?</p>
  
  <p>An example use case would be... I want to list ALL comments in the system on a page.  Essentially using the comments resource as if it's not nested when a user hits   /comments </p>
  
  <p>thank you!</p>