Update README.md

Author: jgperrin

docs/README.md

@@ -270,7 +270,7 @@ Additional metadata options to more accurately define the data type.
 | array          | maxItems         | Maximum Items      | No       | Maximum number of items.                                                                                                                                                                              |
 | array          | minItems         | Minimum Items      | No       | Minimum number of items.                                                                                                                                                                              |
 | array          | uniqueItems      | Unique Items       | No       | If set to true, all items in the array are unique.                                                                                                                                                    |
-| date           | format           | Format             | No       | Format of the date. Follows the format as prescribed by [JDK DateTimeFormatter](https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html). For example, format 'yyyy-MM-dd'. |
+| date           | format           | Format             | No       | Format of the date. Follows the format as prescribed by [JDK DateTimeFormatter](https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html). Default value is using ISO 8601: 'YYYY-MM-DDTHH:mm:ss.SSSZ'. For example, format 'yyyy-MM-dd'. |
 | date           | exclusiveMaximum | Exclusive Maximum  | No       | If set to true, all values are strictly less than the maximum value (values < maximum). Otherwise, less than or equal to the maximum value (values <= maximum).                                       |
 | date           | exclusiveMinimum | Exclusive Minimum  | No       | If set to true, all values are strictly greater than the minimum value (values > minimum). Otherwise, greater than or equal to the minimum value (values >= minimum).                                 |
 | date           | maximum          | Maximum            | No       | All date values are less than or equal to this value (values <= maximum).                                                                                                                             |