add whatsnew entry

Author: haampie

doc/source/whatsnew/v3.0.0.rst

@@ -73,6 +73,7 @@ Other enhancements
 - Support passing a :class:`Iterable[Hashable]` input to :meth:`DataFrame.drop_duplicates` (:issue:`59237`)
 - Support reading Stata 102-format (Stata 1) dta files (:issue:`58978`)
 - Support reading Stata 110-format (Stata 7) dta files (:issue:`47176`)
+- Improved deprecation message for offset aliases (:issue:`60820`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_300.notable_bug_fixes: