dice collection updated!

I added a problem, #57 of now 80 problems. It is the problem of creating a single die with distinct integer faces such that when we roll twice, sum and add one, we always get a prime. This is really just a simpler version of problem 56, but I thought I would add it anyway, since it's kind of fun.

https://www.madandmoonly.com/doctormatt/mathematics/dice1.pdf