[bug]: Errors in readme

[Gokul Suresh]

Issue:

While trying out Hoppscotch/UI on a local project the installation methods mentioned in the README were not correct.

Errors encountered are:

1. Hoppui is not a default export
2. Import error in tailwind config
3. styles were not imported properly

[Liyas Thomas]

@anwarulislam can you look into this issues?