fix doc complaint listed in #353
fix doc complaint listed in #353

radiantbluetechnologies/PDAL,mpgerlek/PDAL-old,mtCarto/PDAL,lucadelu/PDAL,mtCarto/PDAL,boundlessgeo/PDAL,DougFirErickson/PDAL,mtCarto/PDAL,DougFirErickson/PDAL,jwomeara/PDAL,radiantbluetechnologies/PDAL,boundlessgeo/PDAL,mtCarto/PDAL,jwomeara/PDAL,boundlessgeo/PDAL,Sciumo/PDAL,jwomeara/PDAL,mpgerlek/PDAL-old,DougFirErickson/PDAL,DougFirErickson/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,Sciumo/PDAL,lucadelu/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,Sciumo/PDAL,lucadelu/PDAL,jwomeara/PDAL,radiantbluetechnologies/PDAL,mpgerlek/PDAL-old,mpgerlek/PDAL-old