title: Adding model-wide help text to a django model's admin form
body: <p>In my django app, I would like to be able to add customized help text to the admin change form for some of my models.  Note I'm not talking about the field specific <code>help_text</code> attribute that I can set on individual fields.  For example, at the top of the change form for <code>My_Model</code> in <code>My_App</code> I'd like to be able to add some HTML that says "For additional information about My Model, see <a href="http://example.com" rel="noreferrer">http://example.com</a>" in order to provide a link to an internal documentation wiki.</p>
  
  <p>Is there any simple way of accomplishing this, or do I need to create a custom admin form for the model?  If so, can you give me an example of how I would do that?</p>