Documenting engageadx adaptor alias (#2959)

Documenting prebid/Prebid.js#6608

dev-docs/bidders/engageadx.md

@@ -0,0 +1,27 @@
+---
+layout: bidder
+title: EngageADX
+description: EngageADX Bidder Adaptor
+pbjs: true
+pbs: true
+biddercode: engageadx
+media_types: banner, native, video
+gdpr_supported: true
+usp_supported: true
+coppa_supported: true
+pbs_app_supported: true
+schain_supported: true
+aliasCode : adkernel
+---
+
+### Note:
+
+The EngageADX bidding adapter requires setup and approval before implementation. Please reach out to <[email protected]> for more details.
+
+### Bid Params
+
+{: .table .table-bordered .table-striped }
+| Name     | Scope    | Description           | Example                   | Type     |
+|----------|----------|-----------------------|---------------------------|----------|
+| `host`   | required | Host | `'cpm.engageadx.com'` | `string` |
+| `zoneId` | required | Zone Id           | `30164`                 | `integer` |