Update live/portfolio/read response

[Marinovsky]

Update docs response from live/portfolio/read to match the response from the API:

{
    "portfolio": {
        "holdings": {
            "AAPL R735QTJ8XC9X": {
                "symbol": {
                    "value": "AAPL",
                    "id": "AAPL R735QTJ8XC9X",
                    "permtick": "AAPL"
                },
                "currencySymbol": "$",
                "averagePrice": 1,
                "quantity": 1,
                "marketPrice": 183.28999999999999,
                "conversionRate": 1,
                "marketValue": 183.28977991799999,
                "unrealizedPnl": 181.28999999999999,
                "unrealizedPnLPercent": 18128.98,
                "type": 1
            }
        },
        "cash": {
            "USD": {
                "securitySymbols": [],
                "symbol": "USD",
                "amount": 100000,
                "conversionRate": 1,
                "currencySymbol": "$",
                "valueInAccountCurrency": 100000
            }
        }
    },
    "success": true
}