tweak whatsnew entry.

Author: ResidentMario

doc/source/whatsnew/v0.20.0.txt

@@ -160,7 +160,7 @@ Other enhancements
 - ``Series.sort_index`` accepts parameters ``kind`` and ``na_position`` (:issue:`13589`, :issue:`14444`)
 
 - ``DataFrame`` has gained a ``nunique()`` method to count the distinct values over an axis (:issue:`14336`).
-- ``DataFrame`` has gained a ``melt()`` method for unpivoting from a wide to long format (:issue:`12640`).
+- ``DataFrame`` has gained a ``melt()`` method, equivalent to ``pd.melt()``, for unpivoting from a wide to long format (:issue:`12640`).
 - ``DataFrame.groupby()`` has gained a ``.nunique()`` method to count the distinct values for all columns within each group (:issue:`14336`, :issue:`15197`).
 
 - ``pd.read_excel`` now preserves sheet order when using ``sheetname=None`` (:issue:`9930`)