Update readme file with instruction to setup the app with RN 0.71

[shehand]

This is the following up issue for the issue #162

[aaditya9899]

hey can i work upon this its pretty easy and i am just setup the code locally

[shehand]

@aaditya9899 this is the following up issue for the issue #162. If you want to do this, you need to address that issue first.

[ajaman190]

Hi @shehand, could you kindly provide an overview of the format being used for the readme file here?

[ajaman190]

Hello, @shehand. Does ScoreLab have any community on Slack, Discord, or any other platform for GSOC contributors?

[shehand]

@ajaman190 there is no such format. Ideally it should be simple and should provide the overview of setting up the development workspace.

[ajaman190]

Hello @shehand, please review the pull request I have submitted.

[ajaman190]

@shehand , I have raised a new PR please review it.