HDRP: Add comment to light data

com.unity.render-pipelines.high-definition/HDRP/Lighting/Light/HDAdditionalLightData.cs

             {
                 // Note: We can't access to the light component in OnAfterSerialize as it is not init() yet,
                 // so instead we use a boolean to do the upgrade in OnEnable().
+                // However OnEnable is not call when the light is disabled, so the HDLightEditor also call
+                // the UpgradeLight() code in this case
                 needsIntensityUpdate_1_0 = true;
             }
         }