Explain what DAE stands for

Superseded #366.

(cherry picked from commit bdf55bf148dbba76217d96ab3a8e329f4bee986a)

learning/features/3d/importing_3d_scenes.rst

@@ -85,8 +85,9 @@ Source & target paths
 ~~~~~~~~~~~~~~~~~~~~~
 
 To import, two options are needed. The first is a source .dae file
-(.dae stands for Collada. More import formats will eventually added,
-but Collada is the most complete open format as of this writing).
+("Digital Asset Exchange", the extension of the Collada standard).
+More import formats will eventually added, but Collada is the most
+complete open format as of this writing.
 
 A target folder needs to be provided, so the importer can import the
 scene there. The imported scene will have the same filename as the