Addressed ONNX module documentation warnings and added notes for shor…

…t-form representation (#13259)

python/mxnet/contrib/onnx/mx2onnx/export_model.py

@@ -58,6 +58,11 @@ def export_model(sym, params, input_shape, input_type=np.float32,
     -------
     onnx_file_path : str
         Onnx file path
+
+    Notes
+    -----
+    This method is available when you ``import mxnet.contrib.onnx``
+
     """
 
     try:

python/mxnet/contrib/onnx/onnx2mx/import_model.py

@@ -41,6 +41,11 @@ def import_model(model_file):
 
     aux_params : dict of ``str`` to :class:`~mxnet.ndarray.NDArray`
         Dict of converted parameters stored in ``mxnet.ndarray.NDArray`` format
+
+    Notes
+    -----
+    This method is available when you ``import mxnet.contrib.onnx``
+
     """
     graph = GraphProto()
 
@@ -58,6 +63,10 @@ def get_model_metadata(model_file):
     """
     Returns the name and shape information of input and output tensors of the given ONNX model file.
 
+    Notes
+    -----
+    This method is available when you ``import mxnet.contrib.onnx``
+
     Parameters
     ----------
     model_file : str

python/mxnet/contrib/onnx/onnx2mx/import_to_gluon.py

@@ -36,6 +36,11 @@ def import_to_gluon(model_file, ctx):
     -------
     sym_block : :class:`~mxnet.gluon.SymbolBlock`
         A SymbolBlock object representing the given model file.
+
+    Notes
+    -----
+    This method is available when you ``import mxnet.contrib.onnx``
+
     """
     graph = GraphProto()
     try: