docs: update docstring of Container class

openedx_learning/apps/authoring/containers/models.py

@@ -69,6 +69,15 @@ class EntityListRow(models.Model):
 
 class Container(PublishableEntityMixin):
     """
+    A Container is a type of PublishableEntity that holds other
+    PublishableEntities. For example, a "Unit" Container might hold several
+    Components.
+
+    For now, all containers have a static "entity list" that defines which
+    containers/components/enities they hold. As we complete the Containers API,
+    we will also add support for dynamic containers which may contain different
+    entities for different learners or at different times.
+
     NOTE: We're going to want to eventually have some association between the
     PublishLog and Containers that were affected in a publish because their
     child elements were published.