chore: import upstream snapshot with attribution

code/_convenience_scripts/blank_tocs/ch02.toc

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+Artificial neurons - a brief glimpse into the early history
+of machine learning
+Implementing a perceptron learning algorithm in Python
+  Training a perceptron model on the Iris dataset
+Adaptive linear neurons and the convergence of learning
+  Minimizing cost functions with gradient descent
+  Implementing an Adaptive Linear Neuron in Python
+  Large scale machine learning and stochastic gradient descent
+Summary