message: describe building & running on tpu
diff: @@ -117,6 +117,7 @@ The choice of which engine to use is controlled by the command line argument
  ## TensorFlow Lite
  Minigo supports Tensorflow Lite as an inference engine.
  +Build `//cc:main` with `--define=lite=1` and run with `--engine=lite`.
  First, run a frozen graph through Toco, the TensorFlow optimizing compiler:
  @@ -143,8 +144,11 @@ bazel build -c opt --define=tf=0 --define=lite=1 cc:main
  ## Cloud TPU
  -Minigo supports running inference on Cloud TPU. To freeze a model into a
  -GraphDef proto that can be run on Cloud TPU, use `freeze_graph.py`:
  +Minigo supports running inference on Cloud TPU.
  +Build `//cc:main` with `--define=tpu=1` and run with `--engine=tpu`.
  +
  +To freeze a model into a GraphDef proto that can be run on Cloud TPU, use
  +`freeze_graph.py`:
  ```
  BOARD_SIZE=19 python freeze_graph.py \
  