fixed rounding

[ben-schwen]

Hi Christoph, first of all thanks for the great book.

However, there are some minor rounding errors on page 77 of the book, which are due to the fact that the exp is taken of the "exact" values while both the exact values and the exp values are rounded and then printed with kable. This especially catches one's eye with 0.82 whose exp rounded is 2.27 and not 2.26.

[christophM]

Thanks Ben!