We previously wrote about Propy using blockchain technology to smooth real-world real estate sales by introducing the concept of smart contracts. Propy was the first blockchain startup to make that work. Now the company is pushing the boundaries again, by auctioning a real apartment as an NFT. Although one might want to brush this aside as a stunt, the event is designed to make the point that it could well be done legally. And, by golly, they are going to try. The auction will be of the NFT attached to…