Add whats new note

Author: ryankarlos

doc/source/whatsnew/v1.0.0.rst

@@ -999,7 +999,7 @@ Reshaping
 - Bug in :func:`melt` where supplying mixed strings and numeric values for ``id_vars`` or ``value_vars`` would incorrectly raise a ``ValueError`` (:issue:`29718`)
 - Dtypes are now preserved when transposing a ``DataFrame`` where each column is the same extension dtype (:issue:`30091`)
 - Bug in :func:`merge_asof` merging on a tz-aware ``left_index`` and ``right_on`` a tz-aware column (:issue:`29864`)
--
+- Improved error message and docstring in :func:`cut` and :func:`qcut` when `labels=True` (:issue:`13318`)
 
 Sparse
 ^^^^^^