[DOCS] add how to get Spotify client and secret ID

[Dun-sin]

Description

Add these instructions to the Readme, after Installation section:

## How to get the client ID and Secret ID from spotify
  - Go to [spotify for Developers](https://developer.spotify.com/)
  - Login to your spotify Account
  - Go to [your dashboard](https://developer.spotify.com/dashboard)
  - [Create a new App](https://developer.spotify.com/dashboard/create)
  - Fill in the app name `hearitfresh`, description as whatever you want, and the redirect urls to be `http://localhost:3000`, click on add and at the bottom of the page click on save
    ![Demo Screenshot](https://github.com/user-attachments/assets/913ae140-d95b-495b-bc1f-0d0c5d2c8222)
  - After the project is created, go to settings and you'll find the client secret and ID to use
  - Copy them and fill them in the env file as SPOTIFY_CLIENT_ID & SPOTIFY_CLIENT_SECRET, respectively

Note: Make sure to read and understood the rules in the Contributing Guidelines

[akadeepesh]

I'm on it!

[Dun-sin]

Hi @akadeepesh , thanks for wanting to fix this issue, but i would like to leave it up for someone new to the project or open source in general. You can check out the rest of the issues or use the application to see what you can add.

[Aditya7pandey]

Please assign this to me

[Dun-sin]

Please assign this to me

Sure @Aditya7pandey, thanks for wanting to contribute. Make sure to read the issue description carefully and ask if you have questions. Follow the rules here, or your PR won't be accepted and will be closed. Good luck!

[Aditya7pandey]

I have created the pull request please review it.