Add dataset summary figures for building

README.md

@@ -38,6 +38,8 @@ This dataset is intended for training models to predict building coverage as con
 <!-- phi2fm-dataset-figures:start -->
 ## Dataset Visual Summary
 
+The figures below are designed for quick visual inspection rather than quantitative evaluation. Each representative panel shows the source image, a label overlay, and an adaptive heatmap that makes sparse targets easier to inspect.
+
 - Samples: `676`
 - Image shape: `(8, 5263, 3797)`
 - Label shape: `(1, 5263, 3797)`