MultinomialNB (#32)

feat: add MultinomialNB

src/naive_bayes/mod.rs

@@ -66,5 +66,8 @@ impl<T: RealNumber, M: Matrix<T>, D: NBDistribution<T, M>> BaseNaiveBayes<T, M,
 }
 mod categorical;
 mod gaussian;
+mod multinomial;
+
 pub use categorical::{CategoricalNB, CategoricalNBParameters};
 pub use gaussian::{GaussianNB, GaussianNBParameters};
+pub use multinomial::{MultinomialNB, MultinomialNBParameters};