message: Add links to the C-api, and bazel-subproject instructions.
diff: @@ -7,6 +7,12 @@ You should, as a result, be sure you are following the
  [`master` version of this doc](https://www.tensorflow.org/versions/master/api_guides/cc/guide),
  in case there have been any changes.
  +Note: The C++ API is only designed to work with TensorFlow `bazel build`.
  +If you need a stand-alone option use the [C-api](../../install/install_c.md).
  +See [these instructions](https://docs.bazel.build/versions/master/external.html)
  +for details on how to include TensorFlow as a subproject (instead of building
  +your project from inside TensorFlow, as in this example).
  +
  [TOC]
  TensorFlow's C++ API provides mechanisms for constructing and executing a data
  