Adding ONNX model hosting example link (onnx#107)

Adding ONNX model hosting on AWS SageMaker example notebook.

Author: lupesko

README.md

@@ -34,6 +34,7 @@ ONNX is supported by [a community of partners](https://onnx.ai/supported-tools),
 
 * For serving
  * [Serving ONNX models with MXNet Model Server](tutorials/ONNXMXNetServer.ipynb)
+ * [ONNX model hosting with AWS SageMaker and MXNet](https://github.com/awslabs/amazon-sagemaker-examples/blob/master/sagemaker-python-sdk/mxnet_onnx_eia/mxnet_onnx_eia.ipynb) 
 
 * For conversion
  * [Convert a PyTorch model to Tensorflow using ONNX](tutorials/PytorchTensorflowMnist.ipynb)