fix: change datetime widget value format (#7072)

- from 12-hour to 24-hour format
- replace moment references in the docs

#7066

Co-authored-by: Anze Demsar <[email protected]>

Author: martinjagodic

packages/decap-cms-widget-datetime/src/DateTimeControl.js

@@ -119,7 +119,7 @@ export default class DateTimeControl extends React.Component {
         <input
           id={forID}
           type="datetime-local"
-          value={dayjs(value).format('YYYY-MM-DDThh:mm')}
+          value={dayjs(value).format('YYYY-MM-DDTHH:mm')}
           onChange={e => this.handleChange(dayjs(e.target.value))}
           onFocus={setActiveStyle}
           onBlur={setInactiveStyle}

website/content/docs/widgets/datetime.md

@@ -7,12 +7,12 @@ The datetime widget translates a datetime picker to a datetime string.
 
 - **Name:** `datetime`
 - **UI:** datetime picker
-- **Data type:** Moment.js-formatted datetime string
+- **Data type:** [Day.js](https://day.js.org/)-formatted datetime string
 - **Options:**
   - `default`: accepts a datetime string, or an empty string to accept blank input; otherwise defaults to current datetime
-  - `format`: sets storage format; accepts Moment.js [tokens](https://momentjs.com/docs/#/parsing/string-format/); defaults to raw Date object (if supported by output format)
-  - `date_format`: sets date display format in UI; boolean or Moment.js [tokens](https://momentjs.com/docs/#/parsing/string-format/). If `true` use default locale format.
-  - `time_format`: sets time display format in UI; boolean or Moment.js [tokens](https://momentjs.com/docs/#/parsing/string-format/). If `true` use default locale format, `false` hides time-picker.
+  - `format`: sets storage format; accepts [Day.js formats](https://day.js.org/docs/en/display/format); defaults to ISO8601 (if supported by output format)
+  - `date_format`: sets date display format in UI; boolean or [Day.js formats](https://day.js.org/docs/en/display/format). If `true` use default locale format.
+  - `time_format`: sets time display format in UI; boolean or [Day.js formats](https://day.js.org/docs/en/display/format). If `true` use default locale format, `false` hides time-picker.
   - `picker_utc`: _(default: `false`)_ when set to `true`, the datetime picker will display times in UTC. When `false`, the datetime picker will display times in the user's local timezone. When using date-only formats, it can be helpful to set this to `true` so users in all timezones will see the same date in the datetime picker.
 - **Example:**
     ```yaml