message: Update README.md with installation instructions
  Update README.md to include installation instructions.
diff: @@ -14,6 +14,28 @@ $ bazel build build_pip_pkg
  $ bazel-bin/build_pip_pkg artifacts
  ```
  +A package file `artifacts/tensorflow_io-*.whl` will be generated after a build is successful.
  +
  +## Installation
  +
  +Once a package file `artifacts/tensorflow_io-*.whl` is ready, installation could be done through:
  +```
  +$ pip install working_dir/artifacts/tensorflow_io-*.whl
  +```
  +
  +The related module could be imported with python:
  +```
  +$ python
  +Python 2.7.6 (default, Nov 13 2018, 12:45:42)
  +[GCC 4.8.4] on linux2
  +Type "help", "copyright", "credits" or "license" for more information.
  +>>> from tensorflow_io.kafka import KafkaDataset
  +>>>
  +```
  +
  +Note that python has to run outside of repo directory itself, otherwise python may not
  +be able to find the correct path to the module.
  +
  ## License
  [Apache License 2.0](LICENSE)
  