updated-readme

[khushmeetkk]

Added the steps to setup the app on windows for android development. These steps were missing in previous iteration.

[mandeeps708]

Thank you @khushmeetkk ji

1. I believe it's better to keep it short as earlier and the steps out of README if the official documentation contains all the steps. Instead we can add detailed steps to a GitHub wiki page or similar. We can add steps to the README that are not a part of the documentation but are absolutely necessary for the installation.

2. Also, this PR has the same/similar instructions added multiple times probably by mistake.

3. And it removes the installation instructions for ios.