In non-daemon mode print a hint as the last line to tell the user how to use the daemon mode

[EugenMayer]

I would not make the daemon mode the new default right away ( even though that will make sense in the end ) - nevertheless we should make the users aware of its existent.

We should print something like "to run this in the background start docker-sync start -d"

[masterful]

I'm thinking about using the global config to only show this message once, or would you prefer it shows up periodically like UpdateCheck, or simply every time?

[EugenMayer]

I guess it won't harm putting it on the end of every non daemon mode startup, it's just one line more. No strong feeling here either way is ok

[EugenMayer]

Also here, great work!