message: Add docs for optimizer
diff: """onnx optimizer
  +This enables users to optimize their models.
  """
  from __future__ import absolute_import
  from __future__ import division
  @@ -8,4 +9,15 @@ from __future__ import unicode_literals
  import onnx.onnx_cpp2py_export.optimizer as C
  +"""Apply the optimization on the serialized ModelProto.
  +
  +Arguments:
  + input (string): serialized ModelProto
  + names (list of string): list of optimization names
  +
  +Supported pass names:
  + -- eliminate_nop_transpose
  + -- fuse_consecutive_transposes
  + -- fuse_transpose_into_gemm
  +"""
  optimize = C.optimize
  