advise on frequency of live pv data uploads

[zakwatts]

Add to the documentation the recommended frequency of live pv data uploads. Model currently forecasts 30 minutes frequency but to ensure most up to date data is used and available in time, data could be uploaded in 5/10/15 minute chunks of average power (in kW)

Also would be good to add how much historic data should be posted when first forecasting to the documenation. (or advise that instead you can wait 7 days for our system to gather enough information about the sites via posting data consistently)