Explicitly mention discord.Object in abc.Snowflake documentation.

discord/abc.py

@@ -51,6 +51,9 @@ class Snowflake(metaclass=abc.ABCMeta):
     Almost all :ref:`Discord models <discord_api_models>` meet this
     abstract base class.
 
+    If you want to create a snowflake on your own, consider using
+    :class:`Object`.
+
     Attributes
     -----------
     id: :class:`int`