modified readme

readme.md

@@ -55,6 +55,11 @@ During the development stage, you will work on [Google Colab](https://colab.rese
 
 If you are not already familiar with Google Colab and Jupyter Notebooks, you can have a look to [this brief overview](https://colab.research.google.com/notebooks/basic_features_overview.ipynb).
 
+If you need a refresher on Machine Learning and Deep Learning, you can have a look to the following cheatsheets:
+
+* [Machine Learning cheatsheet](https://stanford.edu/~shervine/teaching/cs-229/)
+* [Deep Learning cheatsheet](https://stanford.edu/~shervine/teaching/cs-230/)
+
 In order to guide you in this project, you have access to the following Jupyter Notebooks and Python scripts:
 
 * `1-dataset.ipynb`: This notebook introduces the [SONYC-UST dataset](https://zenodo.org/record/2590742#.XIkTPBNKjuM). You will use this dataset in the development stage of your system, i.e. before deploying it on the [Nvidia Jetson Nano](https://developer.nvidia.com/embedded/jetson-nano-developer-kit).