Swapped axes on heatmap in classification notebook

[Campbell]

The axes on the heatmap in the classification notebook are incorrect. Predicted species should be on the horizontal axis and actual species should be on the vertical axis. The scikit-learn documentation for the confusion matrix states that it returns "Confusion matrix whose i-th row and j-th column entry indicates the number of samples with true label being i-th class and prediced label being j-th class."

[Graeme Malcolm]

Nice catch! Fixed throughout.