Add Transmission profile

I think that would be better to share large files not related to Nix/NixOS on lab computers (e.g. Windows images, RNL Virt disks) using torrents instead of the Nix Store.

Since we have a lot of computers in labs it might be a good idea to use a service like Transmission configured in every lab computer and a machine like (Dolly, FTP, or Dollars) to have the files saved and use it like a fixed peer, because we redeploy all labs every year at least.

But to keep track of which torrents are being seeded would be useful to have the torrent file in our NixOS config.