Docs: Update StartIO ID module documentation with storage configuration details

Author: IlliaMil

modules/startioIdSystem.md

@@ -38,3 +38,7 @@ The below parameters apply only to the Start.io User ID integration.
 | Param under userSync.userIds[] | Scope | Type | Description | Example |
 | --- | --- | --- | --- | --- |
 | name | Required | String | The name of this module. | `"startioId"` |
+| storage | Required | Object | Storage configuration for the user ID. | |
+| storage.type | Required | String | Type of storage: `"cookie"`, `"html5"`, or `"cookie&html5"`. | `"cookie&html5"` |
+| storage.name | Required | String | The name used to store the user ID. | `"startioId"` |
+| storage.expires | Optional | Number | Number of days before the stored ID expires. Defaults to `90`. | `365` |