Add comment.

Author: ilan-gold

diffxpy/testing/det.py

@@ -791,6 +791,7 @@ def _ave(self):
 
         :return: np.ndarray
         """
+        # https://github.com/dask/dask/issues/7169
         x = self.x
         if isinstance(x, dask.array.core.Array):
             x = x.compute()