Adding CONTRIBUTING.md

[bariscanyilmaz]

CONTRIBUTING.md file is missing.
If you develop an open source project and want people to contribute your project this file will be helpful.

Contributing file should have a guideline for others how they can make development to this project.

• Environments like which tools used in this project.
• How people should open an issue or send pull request.
• Naming conventions for code and commit messages.

This article and project can give more information.

[umutsevdi]

The contribution option is going to be added when the "Remake" version is released. That version will also contain detailed information about the project.