Make syncthing better for demon work on *nix

[Rewt0r (Michael Jephcote)]

@canton7

It’s important to note that Syncthing is a user-level application, which synchronizes a user’s files. It should not be given access to system files, nor run with root permissions.

This is very important, my how-to (albeit, slightly outdated) gives you step by step instructions on how to get it running as a certain user as a service and how to use journalctl to view output.