Fixing the `poly2herm` example import line

Just a quick commit fixing the `import` line on the `poly2herm` [example](http://docs.scipy.org/doc/numpy/reference/generated/numpy.polynomial.hermite.poly2herm.html#numpy.polynomial.hermite.poly2herm)

It was originally using the same `import` line from the `poly2herme` [example](http://docs.scipy.org/doc/numpy/reference/generated/numpy.polynomial.hermite_e.poly2herme.html#numpy.polynomial.hermite_e.poly2herme)