introduction about coding style (#69)

* DOC: introduction about coding style

Author: facaiy

CONTRIBUTING.md

@@ -51,7 +51,8 @@ us**
 ## Development Environment
 It is recommended that development is done in the latest
 `nightly-custom-op` docker image.
-```
+
+```bash
 docker run --rm -it -v ${PWD}:/addons -w /addons tensorflow/tensorflow:nightly-custom-op /bin/bash
 ```
 
@@ -62,6 +63,12 @@ Try those commands below:
 2. Run unit test: `make unit-test`
 3. All of the above: `make`
 
+## Coding style
+
+Addons provides `make code-format` command to format your changes
+automatically, don't forget to use it before pushing your codes.
+
+Please see our [Style Guide](SYLE_GUIDE.md) for more details.
 
 ## Code Testing
 #### CI Testing
@@ -71,13 +78,15 @@ hardware will be available from our CI provider.
 
 #### Locally Testing
 
-```
+```bash
 docker run --rm -it -v ${PWD}:/addons -w /addons tensorflow/tensorflow:nightly-custom-op make unit-test
 ```
 
 or run manually:
 
-```
+```bash
+docker run --rm -it -v ${PWD}:/addons -w /addons tensorflow/tensorflow:nightly-custom-op /bin/bash
+
 ./configure.sh  # Links project with TensorFlow dependency
 
 bazel test -c opt -k \

README.md

@@ -73,8 +73,8 @@ pip install artifacts/tensorflow_addons-*.whl
 ## Contributing
 TF-Addons is a community led open source project. As such, the project
 depends on public contributions, bug-fixes, and documentation. Please
-see [CONTRIBUTING.md](CONTRIBUTING.md) for a guide on how to contribute.
-This project adheres to [TensorFlow's code of conduct](CODE_OF_CONDUCT.md).
+see [contribution guidelines](CONTRIBUTING.md) for a guide on how to
+contribute. This project adheres to [TensorFlow's code of conduct](CODE_OF_CONDUCT.md).
 By participating, you are expected to uphold this code.
 
 ## Community

STYLE_GUIDE.md

@@ -0,0 +1,40 @@
+#### C++
+C++ code should conform to [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html).
+
+Addons uses [clang-format](https://clang.llvm.org/docs/ClangFormat.html)
+to check your C/C++ changes. Sometimes you have some manually formatted
+code that you don’t want clang-format to touch.
+You can disable formatting like this:
+
+```cpp
+int formatted_code;
+// clang-format off
+    void    unformatted_code  ;
+// clang-format on
+void formatted_code_again;
+```
+
+#### Python
+Python code should conform to [PEP8](https://www.python.org/dev/peps/pep-0008/).
+
+Addons uses [yapf](https://github.com/google/yapf) to format code,
+and [pylint](https://www.pylint.org/) for code analysis.
+You can disable them locally like this:
+
+```python
+# yapf: disable
+FOO = {
+    # ... some very large, complex data literal.
+}
+
+BAR = [
+    # ... another large data literal.
+]
+# yapf: enable
+```
+
+```python
+# pylint: disable=protected-access
+foo._protected_member
+# pylint: enable=protected-access
+```