moved docs to 0.17

Author: Nick Eubank

doc/source/whatsnew/v0.17.0.txt

@@ -20,6 +20,13 @@ Check the :ref:`API Changes <whatsnew_0170.api>` and :ref:`deprecations <whatsne
 
 New features
 ~~~~~~~~~~~~
+- ``merge`` now accepts the argument ``indicator``. If ``True``, adds a column to output DataFrame called ``_merge`` with information on the source of each row. ``_merge`` is Categorical-type and takes on a value of ``left_only`` for observations whose merge key only appears in ``'left'`` DataFrame, ``right_only`` for observations whose merge key only appears in ``'right'`` DataFrame, and ``both`` if the observation's merge key is found in both. (:issue:`7412` and :issue:`8790`.)
+
+  .. ipython:: python
+
+    df1 = pd.DataFrame({'col1':[0,1], 'col_left':['a','b']})
+    df2 = pd.DataFrame({'col1':[1,2,2],'col_right':[2,2,2]})
+    pd.merge(df1, df2, on='col1', how='outer', indicator=True)
 
 .. _whatsnew_0170.enhancements.other: