message: Add OWNERS for MetaGraphDef Transform Tool.
  (Also, a docstring nit re the sparsify_gather transform).
diff: @@ -706,7 +706,8 @@ def meta_graph_transform(
  output_names: Names of output nodes.
  transforms: A list of strings naming the graph transforms to be applied in
  order. These transform names are exactly those supported by the Graph
  - Transform Tool, with the addition of the 'freeze_graph' transform.
  + Transform Tool, with the addition of the 'freeze_graph' and
  + 'sparsify_gather' transforms.
  tags: A list of tags with which to annotate the transformed MetaGraphDef.
  checkpoint_path: A path to a checkpoint to restore during freezing,
  if needed (default None).
  