node: add comment about --nousb being deprecated (#23439)

Co-authored-by: Felix Lange <fjl@twurst.com>

node/config.go

@@ -93,6 +93,7 @@ type Config struct {
 	InsecureUnlockAllowed bool `toml:",omitempty"`
 
 	// NoUSB disables hardware wallet monitoring and connectivity.
+	// Deprecated: USB monitoring is disabled by default and must be enabled explicitly.
 	NoUSB bool `toml:",omitempty"`
 
 	// USB enables hardware wallet monitoring and connectivity.