title: Active Model Serializers: How to pass options to a collection?
body: <p>If I have a collection of something, say Widgets, and I'm using Active Model Serializers to serialize the collection of Widgets, how do I pass instance_options to a collection?</p>
  
  <pre><code>render json: @widgets, count: 40
  </code></pre>
  
  <p>I tried the above and I can't seem to get <code>count: 40</code> in my <code>instance_options</code>. Am I missing something?</p>