That's what i'm talking about but it's seems outdated/abandoned and it's only cover small area of modding.
Something more complex which would allow to create item from 0 to finish, like creating item then adding it to specific locations/containers to spawn then setting spawn chance, adding it to various recipes etc. and that's for items only but there are many other things that can be modded. Anyway it would be very nice for community to have offical program dedicated to make modding easier.