confirmation: Add comment explaining RealmCreationKey.

confirmation/models.py

@@ -119,8 +119,13 @@ def __init__(self, url_name: str,
         validity_in_days=settings.INVITATION_LINK_VALIDITY_DAYS)
 }
 
-# Confirmation pathways for which there is no content_object that we need to
-# keep track of.
+# Functions related to links generated by the generate_realm_creation_link.py
+# management command.
+# Note that being validated here will just allow the user to access the create_realm
+# form, where they will enter their email and go through the regular
+# Confirmation.REALM_CREATION pathway.
+# Arguably RealmCreationKey should just be another ConfirmationObjT and we should
+# add another Confirmation.type for this; it's this way for historical reasons.
 
 def check_key_is_valid(creation_key: Text) -> bool:
     if not RealmCreationKey.objects.filter(creation_key=creation_key).exists():