add example for posting prob fx data

[wholmgren]

The basic API documentation isn't enough unless you already understand the way the probabilistic forecasts are handled.

I started writing something but not sure where it would live so I'll stop before I waste time...

The key thing is that you submit one forecast file for each percentile or threshold. Because it’s for only a single percentile, the file has the exact same structure as a deterministic forecast. This means that you and I don’t need to agree on the structure of a more complicated csv file – we just have to agree on the API endpoints. This might be more clear if you navigate around the probabilistic forecasts on the dashboard and you note which pages allow you to upload/download.

When using the HTTP API, you’d start by getting the probabilistic forecast group metadata:

https://api.solarforecastarbiter.org/#tag/Probabilistic-Forecasts/paths/~1forecasts~1cdf~1{forecast_id}/get

The metadata will contain a “contant_values” field with links to the endpoints for the individual percentiles/thresholds. Then you can post data to those endpoints:

https://api.solarforecastarbiter.org/#tag/Probabilistic-Forecasts/paths/~1forecasts~1cdf~1single~1{forecast_id}~1values/post

[wholmgren]

Reordering the options within the prob fx menu would also help.