update whatsnew

Author: HoqueUM

doc/source/whatsnew/v3.0.0.rst

@@ -86,7 +86,7 @@ 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`)
-
+- :meth:`Dataframe.select_by_substr` is a new method to select columns by substring, with the option to ignore case (defaulted to true) (:issue:`61319`)
 .. ---------------------------------------------------------------------------
 .. _whatsnew_300.notable_bug_fixes: