Compendium update

The derivation of how to rewrite theorem 4.3 (slide 24 in the lecture on simple sampling) was included in the compendium but for the biased estimate using the denominator n. I have now rewritten pp. 28-31 in the compendium so that the formula for the denominator n - 1 is explained.

This update also includes a correction to example 2.5, where an observant student has pointed out a computation error.