Refer to concat in root namespace

Author: neinkeinkaffee

doc/source/whatsnew/v1.4.0.rst

@@ -444,7 +444,7 @@ Deprecated Frame.append and Series.append
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 :meth:`DataFrame.append` and :meth:`Series.append` have been deprecated and will be removed in Pandas 2.0.
-Use :func:`pandas.core.reshape.concat` instead (:issue:`35407`).
+Use :func:`pandas.concat` instead (:issue:`35407`).
 
 *Deprecated syntax*