Merge branch 'xgboost_serializer' of github.com:edwardjkim/sagemaker-python-sdk into xgboost_serializer

Author: edwardjkim

doc/v2.rst

@@ -333,6 +333,11 @@ TensorFlow Serving Predictor
 ``sagemaker.tensorflow.serving.Predictor`` has been renamed to :class:`sagemaker.tensorflow.model.TensorFlowPredictor`.
 (For the previous implementation of that class, see `Deprecate Legacy TensorFlow <#deprecate-legacy-tensorflow>`_).
 
+XGBoost Predictor
+~~~~~~~~~~~~~~~~~
+
+The default seriazlier of ``sagemaker.xgboost.model.XGBoostPredictor`` has been changed from ``NumpySerializer`` to ``LibSVMSerializer``.
+
 
 Inputs
 ------