Proposal to Add LeNet and AlexNet to Unit 2

[kawchar85]

I would like to propose adding two pioneering convolutional neural networks, LeNet and AlexNet, to the content of Unit 2 - Convolutional Neural Networks. The way that both played a great role in the history of deep learning and computer vision could offer a very nice historical context, adding value towards how CNNs have evolved over time. While the current content provides a solid foundation through the covering of state-of-the-art models, integrating LeNet and AlexNet would further deepen our appreciation of the foundational advances that paved the way for modern architectures.