Add default json for for linux-desktop

Author: ThomasFarstrike

osupdate_linux-desktop.json

@@ -0,0 +1,5 @@
+{
+"version": "0.0.0",
+"download_url": "https://nothing-to-see-here.com",
+"changelog": "Over-The-Air Updates are not available for the linux-desktop platform. Sorry!"
+}