Sync backup folder

[arunoruto]

Which addon?
syncthing

Is your feature request related to a problem? Please describe.
It would be nice also to sync the backup folder to a different place.

Describe the solution you'd like
Add the /backup folder to the list of mounted directories.

Describe alternatives you've considered

Additional context

[arunoruto]

Never mind, it seems like the backup folder is mounted but wasn't documented.
Maybe add it to the list of mounted directories in the documentation.