docs: add STYLE_GUIDE.md and update README.md

README.md

@@ -81,4 +81,5 @@ $ swag init
 
 
 ## Contribution
-Learn how to start contribution on the [Contributing Guideline](https://github.com/cloud-barista/docs/tree/master/contributing)
+Learn how to start contribution on the [Contributing Guideline](https://github.com/cloud-barista/docs/tree/master/contributing) and [Style Guideline](https://github.com/cloud-barista/cb-ladybug/blob/master/STYLE_GUIDE.md)
+

STYLE_GUIDE.md

@@ -0,0 +1,26 @@
+
+This document is under work-in-progress.
+
+# Git Commit Message Style
+
+## Commit Messages
+
+### Message Structure
+```
+type: subject
+body
+footer
+```
+
+### The Type
+* feat: a new feature
+* fix: a bug fix
+* docs: changes to documentation
+* style: formatting, missing semi colons, etc; no code change
+* refactor: refactoring production code
+* test: adding tests, refactoring test; no production code change
+* chore: updating build tasks, package manager configs, etc; no production code change
+
+### Other contents
+Reference to Udacity Git Commit Message Style Guide
+  * <https://udacity.github.io/git-styleguide/> (engilish)