quadlet: Embed the correct binary name in the generated comment

The binary name is not the same as in the old quadlet, and can anyway
differ in system and user runs, so use os.Args[0] to get the right name
in the comment.

Signed-off-by: Alexander Larsson <alexl@redhat.com>

cmd/quadlet/main.go

@@ -134,7 +134,7 @@ func generateServiceFile(service *parser.UnitFile) error {
 	Debugf("writing '%s'", service.Path)
 
 	service.PrependComment("",
-		"Automatically generated by quadlet-generator",
+		fmt.Sprintf("Automatically generated by %s", os.Args[0]),
 		"")
 
 	f, err := os.Create(service.Path)