DOC - remove  keyword arg from doctest
DOC - remove  keyword arg from doctest

FrancoisRheaultUS/dipy,villalonreina/dipy,StongeEtienne/dipy,jyeatman/dipy,StongeEtienne/dipy,sinkpoint/dipy,oesteban/dipy,JohnGriffiths/dipy,FrancoisRheaultUS/dipy,oesteban/dipy,JohnGriffiths/dipy,matthieudumont/dipy,rfdougherty/dipy,rfdougherty/dipy,villalonreina/dipy,demianw/dipy,jyeatman/dipy,nilgoyyou/dipy,nilgoyyou/dipy,matthieudumont/dipy,demianw/dipy,sinkpoint/dipy