Changelog for mwc-probability-2.3.1

# Changelog - 2.3.1 (2020-07-31) * Relaxes the upper bound on mwc-random. - 2.3.0 (2020-05-02) * Adds the discrete distribution (like categorical, but with supplied support). - 2.2.0 (2020-01-29) * Adds the Chinese Restaurant Process (crp). - 2.1.0 (2019-07-23) * Generalises 'categorical' and 'multinomial' to take things proportional to probabilities, rather than probabilities proper. - 2.0.4 (2018-06-30) * Clean up docs and add some additional usage information. * Split the existing Student t distribution into 'student' and its generalised variant, 'gstudent'. - 2.0.3 (2018-05-09) * Add inverse Gaussian (Wald) distribution - 2.0.2 (2018-01-30) * Add negative binomial distribution - 2.0.1 (2018-01-30) * Add Normal-Gamma and Pareto distributions - 2.0.0 (2018-01-29) * Add Laplace and Zipf-Mandelbrot distribution * Rename `isoGauss` to `isoNormal` and `standard` to `standardNormal` to uniform naming scheme. * Divide Haddock in sections - 1.3.0 (2016-12-04) * Generalize a couple of samplers to use Traversable rather than lists.