Document DateOnly.AddDays exception (#94635)

Author: ploeh

src/libraries/System.Private.CoreLib/src/System/DateOnly.cs

@@ -115,6 +115,9 @@ public static DateOnly FromDayNumber(int dayNumber)
         /// </summary>
         /// <param name="value">The number of days to add. To subtract days, specify a negative number.</param>
         /// <returns>An instance whose value is the sum of the date represented by this instance and the number of days represented by value.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown if the resulting value would be greater than <see cref="MaxValue"/>.
+        /// </exception>
         public DateOnly AddDays(int value)
         {
             int newDayNumber = _dayNumber + value;