add a debugging tutorial

This tutorial could cover basic debugging steps and common issues.

For example, identifying that the algorithm isn't training due to an incorrectly written objective function, plotting a training curve, checking for overfitting of the CV fold, etc.

No file, test, or entry point is named. Because this repository is marked deprecated and its work moved to the main TPOT project, first confirm the tutorial belongs there and review the active repository's documentation structure. The scope, examples, and completion criteria still need to be defined.

Written by the indexing model from the issue text.