Update Download Hosts: SteamOS

Source/domainset/download.conf

@@ -224,6 +224,9 @@ cdn.kde.org
 invent.kde.org
 # Raspberry Pi
 downloads.raspberrypi.com
+# SteamOS
+steamdeck-images.steamos.cloud
+steamdeck-packages.steamos.cloud
 # CloudSmith
 dl.cloudsmith.io
 # NodeSource