Update distance information

README.md

@@ -15,7 +15,7 @@ For segmentation quality evaluation, we calculate metrics based on three differe
     - mutual information
     - variation of information
 - spatial distance of point clouds
-    - (percentile) hausdorff distance with different distance functions
+    - (percentile) hausdorff distance with different distance functions. Note that this is the distance in voxels based on the grid.
 - spatial overlap of specific regions.
     - accuracy
     - dice dissimilarity