Update synology dockerfile

[Freika]

Hi, I'm a new user and am trying to get it on my Synology to run, according to the documentation. It looks like the docker-compose file from the documentation needs to be updated as well. I'm not really sure how to do it and would appreciate any help. (running in this same error) thanks

Originally posted by @viktor-sc in https://github.com/Freika/dawarich/issues/671#issuecomment-2593812088