Revert "Add back >>> for what's new"

This reverts commit 915dcf5.

Author: ahuang11

doc/whats-new.rst

@@ -1362,7 +1362,7 @@ Enhancements
 - ``core.groupby.GroupBy`` enhancements. By `Deepak Cherian <https://github.com/dcherian>`_.
 
   - Added a repr (:pull:`3344`). Example::
-      >>> da.groupby("time.season")
+   da.groupby("time.season")
       DataArrayGroupBy, grouped over 'season'
       4 groups with labels 'DJF', 'JJA', 'MAM', 'SON'