updated changelog for issue 563

Author: alixdamman

doc/source/changes/version_0_30.rst.inc

@@ -221,7 +221,9 @@ Miscellaneous improvements
 * renamed `a_min` and `a_max` arguments of :py:obj:`LArray.clip()` as `minval` and `maxval` respectively
   and made them optional (closes :issue:`747`).
 
-* improved speed of :py:obj:`read_hdf()` function when reading a stored LArray object (closes :issue:`563`).
+* improved speed of :py:obj:`read_hdf()` function when reading a stored LArray object dumped with
+  the current and future version of larray. To get benefit of the speedup of reading arrays dumped
+  with older versions of larray, please read and re-dump them. Closes :issue:`563`.
 
 
 Fixes