Update screencore.md (#6348)

* enable prebid.js for screencore

* Update screencore.md

Changed placementId from required to optional
Replaced accountId parameter with endpointId

---------

Co-authored-by: Kostiantyn Karchevsky <[email protected]>

Author: screencore-dev

dev-docs/bidders/screencore.md

@@ -32,5 +32,5 @@ Screencore will bid on first impression in request.
 {: .table .table-bordered .table-striped }
 | Name | Scope | Description | Example | Type |
 |---------------|----------|-----------------------|-----------|-----------|
-| `placementId` | required | placement id | `'hash'` | `string` |
-| `accountId` | required | account id | `'id'` | `string` |
+| `placementId` | optional | placement id | `'hash'` | `string` |
+| `endpointId` | optional | endpoint id | `'id'` | `string` |