Add host field into limelight bidder adapter docs (prebid#2048)

Author: imedvedko

dev-docs/bidders/project-limelight.md

@@ -12,5 +12,6 @@ aliasCode: projectLimeLight
 {: .table .table-bordered .table-striped }
 | Name           | Scope      | Description                                                    | Example            |type|
 | :-----------   | :--------- | :------------                                                  | :----------------- |:---|
+| `host` | required | Ad network's RTB host | `'ads.project-limelight.com'` | `string` |
 | `adUnitId` | required   | Ad Unit Id will be generated on Project Limelight Platform. | 0                        |integer|
 | `adUnitType`      | required   | Type of Ad Unit ('video', 'banner')                                             | 'banner'                 |string|