DOC: Updated release notes for 0.20.1 (pandas-dev#16251)

* DOC: Updated release notes for 0.20.1

- Moved whatsnew for 0.20.1 -> 0.20.2 (unreleased)
- Moved whatsnew for 0.20.0 -> 0.20.1 (releasing soon)
- Added release note for pandas-dev#16250

* DOC: Move 0.20.1 to a note

* DOC: Simplify excel style example

Author: TomAugspurger

doc/source/whatsnew/v0.20.0.txt

@@ -1,6 +1,6 @@
 .. _whatsnew_0200:
 
-v0.20.0 (May 4, 2017)
+v0.20.1 (May 5, 2017)
 ---------------------
 
 This is a major release from 0.19.2 and includes a number of API changes, deprecations, new features,
@@ -30,6 +30,11 @@ Highlights include:
 
 Check the :ref:`API Changes <whatsnew_0200.api_breaking>` and :ref:`deprecations <whatsnew_0200.deprecations>` before updating.
 
+.. note::
+
+   This is a combined release for 0.20.0 and and 0.20.1.
+   Version 0.20.1 contains one additional change for backwards-compatibility with downstream projects using pandas' ``utils`` routines. (:issue:`16250`)
+
 .. contents:: What's new in v0.20.0
     :local:
     :backlinks: none
@@ -388,8 +393,7 @@ For example, after running the following, ``styled.xlsx`` renders as below:
    df
    styled = df.style.\
        applymap(lambda val: 'color: %s' % 'red' if val < 0 else 'black').\
-       apply(lambda s: ['background-color: yellow' if v else ''
-                        for v in s == s.max()])
+       highlight_max()
    styled.to_excel('styled.xlsx', engine='openpyxl')
 
 .. image:: _static/style-excel.png