Create API Documentation

# Create API Documentation

### Description
Document the **API endpoints** used in the project. This should include information on what each endpoint does, the request format, and the expected responses.

### Requirements
- **Endpoint Descriptions**: List each API endpoint with a brief description.
- **Request/Response Examples**: Provide example requests and responses for clarity.
- **Error Handling**: Document common error responses and how to handle them.

### Additional Notes
- Use Markdown formatting for better organization (tables, code blocks).
- Link to the API documentation if it exists elsewhere.

### Labels
- `Hacktoberfest`, `documentation`, `good first issue`