minor correction in volume example
minor correction in volume example

jay3sh/vispy,michaelaye/vispy,hronoses/vispy,RebeccaWPerry/vispy,inclement/vispy,RebeccaWPerry/vispy,drufat/vispy,kkuunnddaannkk/vispy,srinathv/vispy,Eric89GXL/vispy,QuLogic/vispy,jdreaver/vispy,sbtlaarzc/vispy,hronoses/vispy,dchilds7/Deysha-Star-Formation,julienr/vispy,dchilds7/Deysha-Star-Formation,ghisvail/vispy,sh4wn/vispy,drufat/vispy,sbtlaarzc/vispy,Eric89GXL/vispy,jay3sh/vispy,srinathv/vispy,RebeccaWPerry/vispy,julienr/vispy,QuLogic/vispy,jdreaver/vispy,QuLogic/vispy,michaelaye/vispy,sh4wn/vispy,Eric89GXL/vispy,julienr/vispy,sbtlaarzc/vispy,jay3sh/vispy,inclement/vispy,jdreaver/vispy,hronoses/vispy,bollu/vispy,inclement/vispy,kkuunnddaannkk/vispy,srinathv/vispy,ghisvail/vispy,michaelaye/vispy,ghisvail/vispy,bollu/vispy,dchilds7/Deysha-Star-Formation,sh4wn/vispy,drufat/vispy,kkuunnddaannkk/vispy,bollu/vispy