fixing doc to reflect the real setup
Using the files account to run both transmission, nginx and sftp. Separated transmission account does not bring extra security. The idea was to protect against using sftp to chnage internal tranmission files that could be used to attacking the transmission itself. However with extra chroot that sshd uses to constrain sftp access this is not necessary and just complicates everytning.
Running nginx and transmission from the same container. A separated container does not improove any security as an exploitable bug in any of these programs allow to run the code under non-root account in the container and that code can just as well start any extra process.