[catboost] update prediction diff tutorial

ref:9e30a9e9e09a1c91f743c1ca8ff2af55a9dbc533

Author: ek-ak

README.md

@@ -51,6 +51,9 @@ It's better to start CatBoost exploring from this basic tutorials.
 * [Feature statistics tutorial](model_analysis/feature_statistics_tutorial.ipynb)
  * This tutorial shows how to calculate feature statistics for catboost model.
 
+* [CatBoost PredictionDiff Feature Importance Tutorial](./prediction_diff_feature_importance_tutorial.ipynb)
+ * This tutorials shows how to use PredictionDiff feature importances.
+
 ## Custom loss
 
 * [Custom Metrics Tutorial](custom_loss/custom_metric_tutorial.md)

model_analysis/README.md

@@ -13,4 +13,7 @@
  * This tutorial shows how to visualize catboost decision trees.
 
 * [Feature statistics tutorial](./feature_statistics_tutorial.ipynb)
- * This tutorial shows how to calculate feature statistics for catboost model.
+ * This tutorial shows how to calculate feature statistics for catboost model.
+
+* [CatBoost PredictionDiff Feature Importance Tutorial](./prediction_diff_feature_importance_tutorial.ipynb)
+ * This tutorials shows how to use PredictionDiff feature importances.