Edit description for SEO.

Author: TimShererWithAquent

articles/spatial-anchors/index.yml

@@ -4,6 +4,7 @@ title: Azure Spatial Anchors Documentation
 metadata:
   title: Azure Spatial Anchors Documentation
   meta.description: Learn how to use Azure Spatial Anchors to build apps with durable spatial anchors.
+  description: Use Azure Spatial Anchors for apps with durable spatial anchors. Learn about authentication, way-finding, experience, logging, and coarse relocalization.
   services: azure-spatial-anchors
   author: craigktreasure
   manager: aliemami

articles/spatial-anchors/unity-overview.md

@@ -1,6 +1,6 @@
 ---
 title: Azure Spatial Anchors Unity overview
-description: Learn how Azure Spatial Anchors can be used within Unity Apps.
+description: Learn how Azure Spatial Anchors can be used within Unity Apps. Review quickstarts for Unity for HoloLens, Unity for Android, and Unity for iOS.
 author: rgarcia
 ms.author: rgarcia
 manager: vriveras