Fix: propshaft missing asset error

[bikash2208]

Description:
This PR updates the README file under the INSTALL (Normal Mode) section to include the bin/rails assets:precompile step, which resolves the Propshaft::MissingAssetError.

Changes Made:

• Updated the INSTALL (Normal Mode) section in the README file to include the following:

$ bundle install
$ EDITOR=vim bundle exec bin/rails credentials:edit # to supply your openai keys
$ bundle exec bin/setup
$ bin/rails assets:precompile
$ bundle exec bin/dev

Testing:

1. Follow the updated README instructions to set up the application.
2. Ensure the error does not appear, and the application starts successfully.

Issue: #23