minor typo fix in comments for UTF8.cs

Author: Nick-Nuon

src/UTF8.cs

@@ -14,7 +14,7 @@ public static class UTF8
         /// <summary>
         /// Given an input buffer <paramref name="pInputBuffer"/> of byte length <paramref name="inputLength"/>,
         /// returns a pointer to where the first invalid data appears in <paramref name="pInputBuffer"/>.
-        /// The parameter <paramref name="Utf16CodeUnitCountAdjustment"/> is set according to the content of the valid UTF-8 characters encountered, counting -1 for each 2-byte character, -2 for each 3-byte character, and -3 for each 4-byte character.
+        /// The parameter <paramref name="Utf16CodeUnitCountAdjustment"/> is set according to the content of the valid UTF-8 characters encountered, counting -1 for each 2-byte character, -2 for each 3-byte and 4-byte characters.
         /// The parameter <paramref name="ScalarCodeUnitCountAdjustment"/> is set according to the content of the valid UTF-8 characters encountered, counting -1 for each 4-byte character.
         /// </summary>
         /// <remarks>