Provide an example for `translation_movements_file`

For this option it would be good to have an example of the value and (more importantly) of the file and / or how to create it.

Furthermore when investigating I couldn't find usage of the vertical translation. So either I just couldn't find it or this is not handled. This is ringing a minor bell inside my memory and maybe we already discuss it @paleo.

If this is not handled at the moment I would be in favor of updating the 'documentation' of the configuration file to clearly advertise it (because if this is not handled then this is misleading):

# A file where each line describes the horizontal and vertical translations of the sample (or detector). The order is 'horizontal, vertical'.
translation_movements_file = 

Maybe adding. something like

# note: at the moment only the horizontal translations are handled