add markers to exams (move away from group based to content based permissions)

templates/author_form.html

@@ -15,6 +15,10 @@
 {% block content %}
 
     <h2>Edit Authors</h2>
+    <p>Authors have full access to access and edit the exam/collection (including the ability to add/remove other authors).</p>
+
+    <p>If you just want a user to be able to mark questions add them as a marker instead.</p>
+
     <form action="" method="post">
         {% csrf_token %}
         <table>