title: Understanding PeeWee's related_name property
body: <p>I'm really enjoying the Peewee ORM. It's lightweight, easy to use, and pretty well documented. One thing I'm having trouble grasping is the <code>related_name</code> property used when implementing foreign keys. I'm never sure whether the property should relate to the table, or to the column. Could someone explain to me exactly what I should be using the name for, and how? For example, with the Student/Courses example found in the Peeewee docs themselves.</p>
  
  <p><a href="https://peewee.readthedocs.org/en/2.0.2/peewee/fields.html#implementing-many-to-many" rel="nofollow">https://peewee.readthedocs.org/en/2.0.2/peewee/fields.html#implementing-many-to-many</a></p>
  
  <pre><code>class Student(Model):
      name = CharField()
  
  class Course(Model):
      name = CharField()
  
  class StudentCourse(Model):
      student = ForeignKeyField(Student)
      course = ForeignKeyField(Course)
  </code></pre>
  
  <p>Assuming I have Student, Course, StudentCourse models. What would the related names be for the StudentCourse columns?</p>