Fix typo and clarify bayesian model

lib/src/models/gaussian.dart

@@ -10,7 +10,10 @@ import 'dart:math';
 /// The model is based on the Normal-Inverse-Gamma distribution.
 /// See https://en.wikipedia.org/wiki/Normal-inverse-gamma_distribution for details.
 /// The formulas used to update the priors can be found under https://en.wikipedia.org/wiki/Conjugate_prior
-/// under "Normal with unkown mean and variance"
+/// under "Normal with unknown mean and variance"
+/// The distribution is model as follows:
+/// $outcome \sim N(\mu, \sigma^2 / l)$
+/// $\sigma^2 \sim IG(\alpha, \beta)$
 class GaussianModel extends SamplingModel {
   final double _mean, _l, _alpha, _beta;