chore: return reviews for a product in example reviews subgraph (#994)

When running queries like the following before the is pr no reviews for
a product were returned.

```graphql
{
  me {
    username
    id
    reviews {
      body
      product {
        upc
      }
    }
    
  }
  topProducts(first: 2) {
    upc
    reviews {
      body
    }
  }
}
```

Co-authored-by: Sergiy 🇺🇦 <[email protected]>