media: Documentation: Add "stream" into glossary

Add term "stream" to the glossary of the Media subsystem documentation.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/userspace-api/media/glossary.rst

@@ -173,6 +173,11 @@ Glossary
 	An integrated circuit that integrates all components of a computer
 	or other electronic systems.
 
+    Stream
+	A distinct flow of data (image data or metadata) from an initial source
+	to a final sink. The initial source may be e.g. an image sensor and the
+	final sink e.g. a memory buffer.
+
     V4L2 API
 	**V4L2 userspace API**