Update documentation for SPC outlook support

docs/troubleshooting.md

@@ -58,7 +58,8 @@ Diagnostic: compare the configured driver with the source driver table in
 Safe fix: correct the driver name. Current drivers include `nws_observation`,
 `nws_alerts`, `nws_forecast_hourly`, `nws_forecast_narrative`,
 `nws_forecast_discussion`, `nws_weatherstories`, `openmeteo_observation`,
-`openmeteo_forecast`, and `openweather_observation`.
+`openmeteo_forecast`, `openweather_observation`, and
+`spc_convective_outlook`.
 
 ## `unknown sink driver`
 
@@ -94,6 +95,20 @@ Diagnostic: inspect the named source in the error and check its `params`.
 Safe fix: add non-empty `url` and `user_agent` values. See
 [HTTP source params](config.md#http-source-params).
 
+SPC convective outlook sources do not use `params.url`; they require
+`latitude`, `longitude`, and `user_agent`. See
+[SPC convective outlook params](config.md#spc-convective-outlook-params).
+
+## `params.latitude is required` Or `params.longitude is required`
+
+Symptom: startup exits for an `spc_convective_outlook` source.
+
+Likely cause: the source is missing one of the configured point coordinates.
+
+Diagnostic: inspect the named SPC source in the error and check its `params`.
+
+Safe fix: add numeric `latitude` and `longitude` values in decimal degrees.
+
 ## `url must include units=metric`
 
 Symptom: startup exits for an `openweather_observation` source.