Tweak wording of location copier question for clarity

[JamesOHeaDLS]

I think the wording of the default location copier question should be made clearer.

Many of the questions refer to a 'beamline shortname', expecting an answer in the form 'i04', b16', etc. However, although the location question also refers to beamline shortname, it expects an answer in the form 'bl04i', bl16b', etc

I suggest the wording could be changed to something like,

"At DLS this should be the beamline name in the form blxxy, or blank for the accelerator"

Maybe a placeholder could be added with an example name too?