Update Readme

So, some screens in the app is already implemented just take a screen shots ```by downloading the app and running in your phone or either fork this repo and run it in you local machine with android studio installed``` and just write below which screens are implemented, as mentioned in readme

For apk checkout the release section in the midhorizontal_right of the your screen

e.g.
if the login screen is implemented just insert the screen shot with height = 400 and width = 200,
the photos should be after the contributing section in readme and before Issues and give this section name as Implemented Screen.
also stack all the photos one after another you can use ```

``` tag.

so it will be like

Contributing

...

Implemented Screens

Screen shots here

Issues

...

從儲存庫的發佈部分下載 APK，或在 Android Studio 中本地執行專案，以查看哪些畫面已實作。擷取每個畫面的螢幕截圖，將其調整為 400x200 像素，並插入 README.md 檔案的「貢獻」和「問題」部分之間，放在新的「已實作畫面」標題下。使用

標籤來堆疊圖片。

由索引模型根據 Issue 內容生成。