Add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,34 @@
+# Contributing
+
+We welcome your contribution!
+
+## How to contribute
+
+### Finding tasks
+
+We use GitHub issues to manage the tasks. Please check here for issues you would like to contribute to. `welcome contribute` and `easy` are good labels to check for the first contribution.
+
+Of course, we also accept Pull Requests which don't have an issue. However, in this case please make sure you explain the motivation, cause, solution, etc in the PR description.
+
+### Start contributing
+
+If you find a task you want to work on, please comment on the issue to prevent conflicts. We'll reply as soon as possible, but you don't need to wait for our reaction, you can start working on the task once you have commented on the issue!
+
+## How to submit a proposal or start a discussion
+
+Issues are preferable, but PRs are also welcome if you have a concrete idea to implement/refactor something. 
+
+## Languages
+
+We use English for issues, comments, and reviews.
+
+English is preferable however; it would be okay in Japanese if you do not want to use English for some reasons. 
+Unfortunately, only English and Japanese are acceptable for us because of our language ability. Thank you for your understanding. JFYI, We at DroidKaigi Committee consists of Japanese speakers and English speakers. 
+
+For non-English speakers, some of DroidKaigi Committee members are not fluent English speakers so don't be afraid of communicating in English. :)
+
+## NOTE
+
+Please don't hesitate to ask questions. 
+
+We would like you to enjoy contributions, learn many things, share your knowledge and enjoy DroidKaigi. Thanks.

README.md

@@ -12,8 +12,7 @@ And also, you can try the binary under development built on master branch throug
 
 # Contributing
 
-We always welcome any and all contributions! See CONTRIBUTING.md for more information  
-// TODO: Add link to CONTRIBUTING.md
+We always welcome any and all contributions! See [CONTRIBUTING.md](CONTRIBUTING.md) for more information  
 
 ## Requirements