Closes #13427: Public model registration (#14152)

* Initial work on #13427

* Clarify documentation

* Reference public models registry when populating models for ConfigTemplate context

netbox/account/models.py

@@ -7,6 +7,8 @@ class UserToken(Token):
     """
     Proxy model for users to manage their own API tokens.
     """
+    _netbox_private = True
+
     class Meta:
         proxy = True
         verbose_name = 'token'