Update ispyb/sp/xtalimaging.py: proper multi-line docstring
Update ispyb/sp/xtalimaging.py: proper multi-line docstring

Co-authored-by: Richard Gildea <ed2546d6617ea3fe35266c10be2eacc180707089@users.noreply.github.com>
DiamondLightSource/ispyb-api,DiamondLightSource/ispyb-api