Merge pull request #1897 from ge0rg/master

Document format of `when:` value

README.md

@@ -345,7 +345,7 @@ PushNotification.localNotification({
   shortcutId: "shortcut-id", // (optional) If this notification is duplicative of a Launcher shortcut, sets the id of the shortcut, in case the Launcher wants to hide the shortcut, default undefined
   onlyAlertOnce: false, // (optional) alert will open only once with sound and notify, default: false
 
-  when: null, // (optionnal) Add a timestamp pertaining to the notification (usually the time the event occurred). For apps targeting Build.VERSION_CODES.N and above, this time is not shown anymore by default and must be opted into by using `showWhen`, default: null.
+  when: null, // (optional) Add a timestamp (Unix timestamp value in milliseconds) pertaining to the notification (usually the time the event occurred). For apps targeting Build.VERSION_CODES.N and above, this time is not shown anymore by default and must be opted into by using `showWhen`, default: null.
   usesChronometer: false, // (optional) Show the `when` field as a stopwatch. Instead of presenting `when` as a timestamp, the notification will show an automatically updating display of the minutes and seconds since when. Useful when showing an elapsed time (like an ongoing phone call), default: false.
   timeoutAfter: null, // (optional) Specifies a duration in milliseconds after which this notification should be canceled, if it is not already canceled, default: null