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

...

Download the APK from the repository's releases section or run the project locally in Android Studio to see which screens are implemented. Take screenshots of each screen, resize them to 400x200 pixels, and insert them in the README.md file between the 'Contributing' and 'Issues' sections under a new 'Implemented Screens' heading. Use

tags to stack the images.

由索引模型根据 Issue 内容生成。