Aloha :)
$$\nabla\nabla\vec r^0=\nabla\nabla\frac{\vec r}{r}=\nabla\nabla\left(\frac{1}{r}\cdot\vec r\right)=\nabla\left(\nabla\left(\frac{1}{r}\right)\cdot\vec r+\frac{1}{r}\cdot\nabla\cdot\vec r\right)$$$$\phantom{\nabla\nabla\vec r^0}=\nabla\left(-\frac{1}{r^2}\,\vec r^0\cdot\vec r+\frac{1}{r}\cdot3\right)=\nabla\left(\frac{2}{r}\right)=-\frac{2}{r^2}\vec r^0=-\frac{2}{r^3}\vec r$$