DOC - fixed typo
DOC - fixed typo

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