message: Add Kokoro Build Status Badge
diff: @@ -106,6 +106,15 @@ version of TensorFlow I/O according to the table below:
  | 0.2.0 | 1.12.0 | Jan 29, 2019 |
  | 0.1.0 | 1.12.0 | Dec 16, 2018 |
  +### Build Status
  +
  +| Build | Status |
  +| --- | --- |
  +| Linux CPU Python 2 | [![Status](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-py2.svg)](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-py2.html) |
  +| Linux CPU Python 3 | [![Status](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-py3.svg)](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-py3.html) |
  +| Linux GPU Python 2| [![Status](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-gpu-py2.svg)](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-gpu-py2.html) |
  +| Linux GPU Python 3| [![Status](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-gpu-py3.svg)](https://storage.googleapis.com/tensorflow-kokoro-build-badges/io/ubuntu-gpu-py3.html) |
  +
  ## Developing
  ### Python
  