Chapter 5 new exercises typos/issues

[sumny]

https://github.com/mlr-org/mlr3book/blob/75ee846c2d2d646cccc343ccc18e879d5f032117/book/chapters/chapter5/advanced_tuning_methods_and_black_box_optimization.qmd#L1120

Pareto-front should be Pareto front. and $x_2 = \left(\sqrt{x_1}-2\right)^2$ with $x_1$ ranging from $0$ to $4$ should be $y_2 = \left(\sqrt{y_1}-2\right)^2$ with $y_1$ ranging from $0$ to $4$ because we are plotting the front, right?

[RaphaelS1]

@mb706 can you check above against exercises doc and make sure they're the same and PR a fix if needed please?

[sumny]

also the new Figure in 5.8 might be easier to visualize when either plotting 1-tpr and fpr or tpr and 1-fpr to either minimize or maximize both metrices.

[mb706]

the idea with the plot is that it looks like a roc plot