Changes single quotes to double quotes

Why: Double quotes don't show up in social media previews

Author: DougReeder

docs/hubs-features.md

@@ -1,7 +1,7 @@
 ---
 id: hubs-features
 title: Hubs Features
-description: 'Hubs user interface: menus for objects, avatars, the camera, and drawing; controls; and spawners'
+description: "Hubs user interface: menus for objects, avatars, the camera, and drawing; controls; and spawners"
 ---
 
 ![Hubs User Interface](img/hubs-user-interface.png)