Update the history

Author: Guillaume Lemaitre

doc/whats_new.rst

@@ -17,6 +17,7 @@ Bug fixes
 
 - Fixed a bug in :class:`under_sampling.NearMiss` which was not picking the right samples during under sampling for the method 3. By `Guillaume Lemaitre`_.
 - Fixed a bug in :class:`ensemble.EasyEnsemble`, correction of the `random_state` generation. By `Guillaume Lemaitre`_ and `Christos Aridas`_.
+- Fixed a bug in :class:`ensemble.BalanceCascade`, solve the issue to obtain a single array if desired. By `Guillaume Lemaitre`_.
 
 New features
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