CODE_OF_CONDUCT.md file missing

As of January 1 2019, Mozilla requires that all GitHub projects include this [CODE_OF_CONDUCT.md](https://github.com/mozilla/repo-templates/blob/master/templates/CODE_OF_CONDUCT.md) file in the project root. The file has two parts:

1. Required Text - All text under the headings *Community Participation Guidelines and How to Report*, are required, and should not be altered.
2. Optional Text - The Project Specific Etiquette heading provides a space to speak more specifically about ways people can work effectively and inclusively together. Some examples of those can be found on the [Firefox Debugger](https://github.com/devtools-html/debugger.html/blob/master/CODE_OF_CONDUCT.md) project, and [Common Voice](https://github.com/mozilla/voice-web/blob/master/CODE_OF_CONDUCT.md). (The optional part is commented out in the [raw template file](https://raw.githubusercontent.com/mozilla/repo-templates/blob/master/templates/CODE_OF_CONDUCT.md), and will not be visible until you modify and uncomment that part.)

If you have any questions about this file, or Code of Conduct policies and procedures, please reach out to Mozilla-GitHub-Standards+CoC@mozilla.com.

_(Message COC001)_

首先，將儲存庫根目錄與連結的 Mozilla CODE_OF_CONDUCT.md 範本進行比較。使用必要的 Community Participation Guidelines 和 How to Report 文字新增缺少的根層級檔案，然後確認檔案存在且必要文字未被變更；依照專案的需求處理選用的 Project Specific Etiquette 區段。

由索引模型根據 Issue 內容生成。