DOC: docstring added for slider
DOC: docstring added for slider

StongeEtienne/dipy,FrancoisRheaultUS/dipy,JohnGriffiths/dipy,matthieudumont/dipy,JohnGriffiths/dipy,nilgoyyou/dipy,nilgoyyou/dipy,villalonreina/dipy,StongeEtienne/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy,matthieudumont/dipy