New adapter: emetriq (#5246)

* New Adapter: emetriq

* New Adapater: emetriq

dev-docs/bidders/emetriq.md

@@ -0,0 +1,31 @@
+---
+layout: bidder
+title: emetriq
+description: emetriq Bidder Adapter
+biddercode: emetriq
+aliasCode: appnexus
+tcfeu_supported: true
+gvl_id: 213
+schain_supported: true
+userId: all
+media_types: banner, video, native
+safeframes_ok: true
+deals_supported: true
+pbjs: true
+pbs: true
+prebid_member: false
+multiformat_supported: will-bid-on-any
+sidebarType: 1
+---
+### Bid Params
+
+{: .table .table-bordered .table-striped }
+| Name          | Scope    | Description           | Example   | Type      |
+|---------------|----------|-----------------------|-----------|-----------|
+| `placement_id` (PBS+PBJS) or `placementId` (PBJS) | required | Placement id          | `'32068254'` | `string`  |
+
+emetriq is an aliased bidder for AppNexus.
+
+### Note
+
+For setup with emetriq, please reach out to [[email protected]](mailto:[email protected])