title: Finding source of manage.py subcommand
body: <p>I'm new to django and working on a modern django/Wagtail CMS app that is seeded using the command <code>python manage.py loadfixtures</code>. It seems like <code>loaddata</code> is the more common command, and I'm finding it incredibly difficult to find any documentation on <code>loadfixtures</code> at all. Could anyone point me towards the difference? It appears under the <code>[Core]</code> section of "available subcommands."</p>
  
  <p>As an aside, I'm essentially trying to dump and seed some static page data for the site.</p>