Update warning msg

Author: makbigc

pandas/core/series.py

@@ -572,7 +572,8 @@ def nonzero(self):
         dtype: int64
         """
         msg = ("Series.nonzero() is deprecated "
-               "and will be removed in a future version.")
+               "and will be removed in a future version."
+               "Use np.nonzero() instead")
         warnings.warn(msg, FutureWarning, stacklevel=2)
         return self._values.nonzero()