Update docs for Carbon time-picker

Author: rvsia

packages/react-renderer-demo/src/doc-components/examples-texts/carbon/carbon-time-picker.md

@@ -9,4 +9,22 @@ This component also accepts all other original props, please see [here](https://
 
 ### Timezone
 
-Object of `value`, `label`. Extends [SelectItem component](https://react.carbondesignsystem.com/?path=/story/select--default).
+Extends [SelectItem component](https://react.carbondesignsystem.com/?path=/story/select--default).
+
+|Option|Description|
+|-----|-----------|
+|label|A label of the timezone|
+|value|A value of the timezone used in `new Date('... ${value}')`|
+|showAs|Timezone that will be used to convert the value `value.toLocaleTimeString(..., { ..., timeZone: showsAs })`. Supported timezones can be found [here](https://cloud.google.com/dataprep/docs/html/Supported-Time-Zone-Values_66194188).|
+
+#### value and showAs relationship
+
+To make this component work, please provide corresponding `showAs` for each timezone.
+
+```jsx
+{
+    label: 'PST',
+    value: 'PST',
+    showsAs: 'US/Eastern'
+}
+```