message: Add better docs
diff: namespace tensorflow {
  namespace graph_transforms {
  -// Changes the op type of a specified op.
  +// Remove control depdencies in preparation for inference.
  +// In the tensorflow graph, control dependencies are represented as extra
  +// inputs which are referenced with "^tensor_name".
  +// See node_def.proto for more details.
  Status RemoveControlDependencies(const GraphDef& input_graph_def,
  const TransformFuncContext& context,
  GraphDef* output_graph_def) {
  