DOCS UPDATE: Command update for running Docker Containers and instructions for adding API Keys in frontend folder

### Is this related to an existing part of the documentation?

- [x] Yes, it is related to an existing section

### What needs to be updated?

## 📌 Current Issues in the Installation Guide
The current documentation has two related issues that can cause confusion and runtime failures for new contributors:

1. Outdated Docker command: The installation guide still uses the deprecated docker-compose command. On modern Docker installations (Docker Desktop with Compose v2), this command is no longer available, and users must instead use docker compose.
2. Missing frontend environment variable instructions: The installation guide only mentions .env configuration at the root level. There are no instructions for setting required frontend environment variables (VITE_SUPABASE_URL and VITE_SUPABASE_KEY) inside the frontend directory. As a result, when the frontend is started for the first time, the application crashes due to missing Supabase configuration, without clear guidance on how to resolve it.

## ✨ Proposed Changes

1. Replace all occurrences of:

```
docker-compose up -d
```

with:
```
docker compose up -d
```

Optionally add a short note explaining that Docker Compose v2 is now bundled with Docker Desktop.

2. Add frontend .env setup instructions

Clearly document that the frontend requires its own .env file.

Specify that the following variables must be defined in the frontend directory:
```
VITE_SUPABASE_URL=your_supabase_project_url
VITE_SUPABASE_KEY=your_public_anon_key
```

I want to work on updating the Installation Guide with the above mentioned changes.

### Relevant Documentation Link (if any)

_No response_

### Record

- [x] I agree to follow this project's Code of Conduct
- [x] I want to work on this update