Update README highlighting the features of the app with more screenshots

[Devansh-Maurya]

The README already has some information regarding the app, thanks to this pull request by @OverPoweredDev . We need more elements to highlight the main features of the app. Adding more screenshots will be preferred. Also, the app has Shishir's Facebook page integrated via Facebook's APIs. Please highlight that too.

Please refer these repos on how to structure the README:

• Cognitia 2018 Android App: https://github.com/NIT-Meghalaya/Cognitia-2018-App
• PukaPuka Android App: https://github.com/Devansh-Maurya/PukaPuka

[OverPoweredDev]

Mind if I work on this? If you want examples of how it'll look there's this repo I made recently or this one

[Devansh-Maurya]

The repos that you linked look good to me. Thanks for picking this up. Will look into the PR 👍