fix : clarify RoundingMode fallback

Author: ShioPy0101

src/Type/Php/RoundFunctionReturnTypeExtension.php

@@ -122,8 +122,10 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 
 	/**
 	 * @return 1|2|3|4|null
-	 * // Fall back to the default return type for RoundingMode cases
-	 * // without a corresponding PHP_ROUND_HALF_* constant.
+	 *
+	 * Returns null for RoundingMode cases without a corresponding
+	 * PHP_ROUND_HALF_* constant, so constant evaluation falls back
+	 * to the existing return-type logic.
 	 */
 	private function resolveRoundMode(Type $modeType): ?int
 	{