docs: expand /api/refinement payload

README.md

@@ -154,7 +154,7 @@ go build -tags sdrplay ./cmd/sdrd
 - `GET /api/gpu`
 - `GET /api/pipeline/policy`
 - `GET /api/pipeline/recommendations`
-- `GET /api/refinement` → latest refinement plan/windows snapshot (includes `window_stats`)
+- `GET /api/refinement` → latest refinement plan/windows snapshot (includes `window_stats`, `decision_summary`, levels)
 
 ### Signals / Events
 - `GET /api/signals` → current live signals