[ImgBot] Optimize images - #1

*Total -- 5,236.95kb -> 3,449.18kb (34.14%)

/img/pixel_numbers.png -- 125.05kb -> 24.77kb (80.19%)
/img/field-3.png -- 110.92kb -> 30.04kb (72.92%)
/img/neural_network-3.png -- 121.33kb -> 36.71kb (69.74%)
/img/ml_prediction.png -- 70.64kb -> 22.38kb (68.31%)
/img/dnn_example-3.png -- 124.17kb -> 39.40kb (68.27%)
/img/mnist_nn.png -- 141.98kb -> 45.19kb (68.17%)
/img/data_windowing.png -- 54.49kb -> 18.05kb (66.88%)
/img/ml_process.png -- 86.72kb -> 28.77kb (66.82%)
/img/neural_network-2.png -- 61.57kb -> 20.90kb (66.05%)
/img/machine_learning.png -- 93.94kb -> 31.98kb (65.96%)
/img/neural_network.png -- 61.85kb -> 21.22kb (65.69%)
/img/reinforcement-learning.png -- 68.25kb -> 23.42kb (65.68%)
/img/dnn_example-2.png -- 154.28kb -> 53.16kb (65.54%)
/img/handwritten_numbers.png -- 554.52kb -> 210.45kb (62.05%)
/img/field-2.png -- 28.00kb -> 10.91kb (61.05%)
/img/field.png -- 21.87kb -> 9.71kb (55.58%)
/img/svm_ex0.png -- 78.44kb -> 36.47kb (53.5%)
/img/k_means.png -- 74.70kb -> 37.65kb (49.6%)
/img/rnn.png -- 343.80kb -> 193.04kb (43.85%)
/img/linear_classifier.png -- 83.31kb -> 48.85kb (41.36%)
/img/svm_ex1.png -- 82.36kb -> 49.47kb (39.93%)
/img/nearest_neighbors.png -- 110.39kb -> 68.79kb (37.68%)
/img/cnn_example.png -- 271.11kb -> 186.32kb (31.28%)
/img/rottweiler.jpg -- 304.36kb -> 261.43kb (14.1%)
/img/word_vectors.png -- 376.33kb -> 358.90kb (4.63%)
/img/dobermann.jpg -- 115.28kb -> 110.37kb (4.26%)
/img/german_shepherd.jpg -- 1,132.12kb -> 1,088.92kb (3.82%)
/img/dnn_example.png -- 385.19kb -> 381.89kb (0.86%)

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