doc: model local mode (#1076)

* Update model.deploy documentation

Author: eric-haibin-lin

src/sagemaker/model.py

@@ -399,7 +399,7 @@ def deploy(
             initial_instance_count (int): The initial number of instances to run
                 in the ``Endpoint`` created from this ``Model``.
             instance_type (str): The EC2 instance type to deploy this Model to.
-                For example, 'ml.p2.xlarge'.
+                For example, 'ml.p2.xlarge', or 'local' for local mode.
             accelerator_type (str): Type of Elastic Inference accelerator to
                 deploy this model for model loading and inference, for example,
                 'ml.eia1.medium'. If not specified, no Elastic Inference