Update README.md

Fixing readme details.

README.md

@@ -247,7 +247,7 @@ Derived from DC-OPF solution to provide reactive power support for AC-OPF conver
 
 ### `_warm_start` — DC Warm-Start Metadata
 
-Present only in the warm-start model files (`*_model.json` after AC-OPF applies shunts), not in the base model.
+Present in all released model files. Contains metadata about the DC-OPF warm-start that was applied before AC-OPF solving (voltage angles injected into buses, reactive shunts added).
 
 | Field | Type | Description |
 |-------|------|-------------|