MINOR: Better image for readme
MINOR: Better image for readme

tylerkidd/silverstripe-versioneddataobjects,heyday/silverstripe-versioneddataobjects,tylerkidd/silverstripe-versioneddataobjects,glenn-bautista/silverstripe-versioneddataobjects,glenn-bautista/silverstripe-versioneddataobjects,heyday/silverstripe-versioneddataobjects