Added reference to glTF

Some readers may not be familiar with 3D formats. Would be great to mention glTF from the beginning, so that the reader knows what to possibly re-use in their own future prototypes.

Author: LazaUK

articles/digital-twins/quickstart-3d-scenes-studio.md

@@ -32,7 +32,7 @@ The scene will look like this:
 
 You'll need an Azure subscription to complete this quickstart. If you don't have one already, [create one for free](https://azure.microsoft.com/free/?WT.mc_id=A261C142F) now.
 
-You'll also need to download a sample 3D file to use for the scene in this quickstart. [Select this link to download RobotArms.glb](https://cardboardresources.blob.core.windows.net/public/RobotArms.glb).
+You'll also need to download a sample glTF (Graphics Language Transmission Format) 3D file to use for the scene in this quickstart. [Select this link to download RobotArms.glb](https://cardboardresources.blob.core.windows.net/public/RobotArms.glb).
 
 ## Set up Azure Digital Twins and sample data
 
@@ -314,4 +314,4 @@ You may also want to delete the downloaded sample 3D file from your local machin
 Next, continue on to the Azure Digital Twins tutorials to build out your own Azure Digital Twins environment.
 
 > [!div class="nextstepaction"]
-> [Code a client app](tutorial-code.md)
+> [Code a client app](tutorial-code.md)