Clarify meaning of highest resolution in docstrings

Co-authored-by: Chahan M. Kropf <[email protected]>

Author: luseverin

climada/entity/exposures/base.py

@@ -618,7 +618,7 @@ def assign_centroids(
             the index `-1` is assigned.
             Set `threshold` to 0, to disable nearest neighbor matching and enforce
             exact matching.
-            Default: twice the highest resolution of the hazard centroids
+            Default: twice the highest resolution (smallest distance between any two nearest neighbours) of the hazard centroids
         overwrite: bool
             If True, overwrite centroids already present. If False, do
             not assign new centroids. Default is True.