fix whatsnew blank line

Author: Dr-Irv

doc/source/whatsnew/v1.5.2.rst

@@ -27,8 +27,9 @@ Fixed regressions
 Bug fixes
 ~~~~~~~~~
 - Bug in the Copy-on-Write implementation losing track of views in certain chained indexing cases (:issue:`48996`)
-- Fixed bug when instantiating a ``DataFrame`` subclass inheriting from ``typing.Generic`` that triggered a ``UserWarning`` on python 3.11 (:issue:49649)
+- Fixed bug when instantiating a :class:`DataFrame` subclass inheriting from ``typing.Generic`` that triggered a ``UserWarning`` on python 3.11 (:issue:49649)
 -
+
 .. ---------------------------------------------------------------------------
 .. _whatsnew_152.other: