normalization documented

src/benchmark_mediation.py

@@ -1123,7 +1123,9 @@ def med_dml(
         Trimming treshold for discarding observations with extreme probability.
 
     normalized : boolean, default=True
-        Normalizes the inverse probability-based weights.
+        Normalizes the inverse probability-based weights so they add up to 1, as
+        described in "Identifying causal mechanisms (primarily) based on inverse probability weighting",
+        Huber (2014), https://doi.org/10.1002/jae.2341
 
     regularization : boolean, default=True
         Whether to use regularized models (logistic or linear regression).