fix formspree and react admin template: correct position field attributes, add env config, remove welcome banner, and updated readme

[Nishantjain10]

What does this PR do?

Key changes include:

• Removed Welcome Banner from react admin template
• src/App.jsx:
  • Corrected the id and name attributes for the position dropdown from "dates" to "position" for better semantics.
  • Replaced the hardcoded Formspree form ID with an environment variable (VITE_FORMSPREE_FORM_ID) to improve security and configuration.
• Project Documentation:
  • Added a comprehensive README.md with detailed setup instructions, environment variable guide, and project structure.
  • Created an env.example file to guide developers on required environment variables.
• Configuration:
  • Updated .gitignore to ensure .env files are not committed to the repository.
  • Updated the envs to earlier envs for react-admin

Test Plan

1. Clone the branch and install dependencies with npm install.
2. Create a .env file by copying env.example.
3. Add your Formspree form ID to the .env file.
4. Run the development server with npm run dev.

Related PRs and Issues

This PR resolves feedback from a code review. (#13)

Have you read the Contributing Guidelines on issues?

Yes, I have.