add readme for wind turbine configs

data/satlas/wind_turbine/README.md

@@ -0,0 +1,8 @@
+`config.json` and `config.yaml` contain the active dataset and model configurations for
+the wind turbine point detection model.
+
+It uses six monthly Sentinel-2 L1C mosaics, which can be spread over up to nine months
+(in case some months don't have enough cloud-free images to form a mosaic).
+
+`config_azure.json` is for testing a model that inputs Sentinel-2 L2A + Sentinel-1
+vv+vh sourced from Microsoft Azure.