title: Render JSON with header
body: <p>I want to render JSON with the following <code>cors</code> header in my controller:</p>
  
  <pre><code>'Access-Control-Allow-Origin' = '*'.
  </code></pre>
  
  <p>I tried this:</p>
  
  <pre><code>def my_action
    render(json: some_params)
    response.headers['Access-Control-Allow-Origin'] = '*'
  end
  </code></pre>
  
  <p>but I got an <code>AbstractController::DoubleRenderError</code>. Are there ways to render JSON with headers?</p>