docs: revise formula - date functions

Signed-off-by: Wing-Kam Wong <wingkwong.code@gmail.com>

packages/noco-docs/content/en/setup-and-usages/formulas.md

@@ -81,12 +81,12 @@ Example: (column1 + (column2 * column3) / (3 - column4 ))
 
 ### Date Functions
 
-| Name        | Syntax                                                    | Sample                                                | Output                                                                                                |
-|-------------|-----------------------------------------------------------|-------------------------------------------------------|-------------------------------------------------------------------------------------------------------|
-| **DATEADD** | `DATEADD(DATE_COL, 1, 'day')`                             | `DATEADD(date, 1, 'day')`                             | Supposing the DATE_COL is 2022-03-14. The result is 2022-03-15.                                       |
-|             | `DATEADD(DATE_TIME_COL, 2, 'month')`                      | `DATEADD(datetime, 2, 'month')`                       | Supposing the DATE_COL is 2022-03-14 03:14. The result is 2022-05-14 03:14.                           |
-|             | `IF(NOW() < DATE_COL, "true", "false")`                   | `IF(NOW() < date, "true", "false")`                   | If current date is less than DATE_COL, it returns true. Otherwise, it returns false.                  |
-|             | `IF(NOW() < DATEADD(DATE_COL,10,'day'), "true", "false")` | `IF(NOW() < DATEADD(date,10,'day'), "true", "false")` | If the current date is less than DATE_COL plus 10 days, it returns true. Otherwise, it returns false. |
+| Name | Syntax | Sample | Output | Remark |
+|---|---|---|---|---|
+| **DATEADD** | `DATEADD(DATE_COL, 1, 'day')` | `DATEADD(date, 1, 'day')` | Supposing the DATE_COL is 2022-03-14. The result is 2022-03-15. | DateTime columns and negative values are supported. Example: `DATEADD(DATE_TIME_COL, -1, 'day')` |
+|  | `DATEADD(DATE_COL, 2, 'month')` | `DATEADD(date, 2, 'month')` | Supposing the DATE_COL is 2022-03-14 03:14. The result is 2022-05-14 03:14. | DateTime columns and negative values are supported. Example: `DATEADD(DATE_TIME_COL, -2, 'month')` |
+|  | `IF(NOW() < DATE_COL, "true", "false")` | `IF(NOW() < date, "true", "false")` | If current date is less than DATE_COL, it returns true. Otherwise, it returns false. | DateTime columns and negative values are supported. |
+|  | `IF(NOW() < DATEADD(DATE_COL,10,'day'), "true", "false")` | `IF(NOW() < DATEADD(date,10,'day'), "true", "false")` | If the current date is less than DATE_COL plus 10 days, it returns true. Otherwise, it returns false. | DateTime columns and negative values are supported. |
 
 ### Logical Operators