Improve Documentation for Local Development Setup

[screwtape151]

Description

The current setup instructions for running the project locally in the README file could benefit from additional detail, particularly for developers who may encounter issues while setting up the environment.

Suggested Improvements:

1. Environment Variables:
   • Include additional details on required environment variables beyond what is mentioned in .env.example. For instance, a brief explanation of the different keys and their purposes would be helpful.
2. Database Setup:
   • Provide a step-by-step guide on how to set up the MongoDB and Redis instances locally or mention if there are required configurations to make them work seamlessly with the backend.
3. Install Dependencies:
   • Clearly indicate the need to install backend dependencies in the backend directory with specific commands, just like it's mentioned for the frontend. E.g., cd backend && npm install.
4. Common Pitfalls:
   • Mention possible issues developers might face and how to resolve them, such as CORS issues, connectivity problems, etc.

By implementing these changes, we can enhance the onboarding experience for new contributors and developers working on the Finance Guide project.