Fix typo on whatsnew

Author: ThomasKluiters

doc/source/whatsnew/v0.25.0.rst

@@ -387,7 +387,7 @@ Reshaping
 - Bug in :func:`concat` where order of ``OrderedDict`` (and ``dict`` in Python 3.6+) is not respected, when passed in as  ``objs`` argument (:issue:`21510`)
 - Bug in :func:`concat` where the resulting ``freq`` of two :class:`DatetimeIndex` with the same ``freq`` would be dropped (:issue:`3232`).
 - Bug in :func:`merge` where merging with equivalent Categorical dtypes was raising an error (:issue:`22501`)
-- Bug in :func:`Series.apply` failed when the series is a timezone aware :class:`DateTimeIndex` (:issue:`25959`)
+- Bug in :func:`Series.apply` failed when the series is a timezone aware :class:`DatetimeIndex` (:issue:`25959`)
 
 Sparse
 ^^^^^^