docs(changes): + 12 arrival classes

Author: TomMonks

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `10_multiple_arrival_processes.ipynb`: simulating multiple arrivals classes each with their own distribution
 * `11_blocking.ipynb`: simulating the blocking of one resource while queuing for another.
+* `12_arrival_classes.ipynb`: simulate unique processes for different classes of arrival to the model.
 * `distributions.py`: module containing some distributions to reduce code in notebooks.
 
 ## [v0.2.0 - 11/02/2024](https://github.com/pythonhealthdatascience/intro-open-sim/releases/tag/v0.2.0) [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.14849934.svg)](https://doi.org/10.5281/zenodo.14849934)