title: How to add custom html or buttons to ActiveAdmin form
body: <p>I have models A and B. A has_many B. In the edit view for A I am 
  displaying all of it's B children using </p>
  
  <pre><code>f.inputs  :for =&gt; :bs do |b|...
  </code></pre>
  
  <p>What I want to do is add a 'delete' link or button after ever 
  B child of A. At the end of the list of B's I'd like to add a 'Add B' 
  button which would create a new B instance and associate it with the 
  current A. This way I can avoid an additional edit view for B (B is a 
  very simple model).</p>