fix: add clarifying comment for stderrthreshold defaults

Address review nit: clarify that flag.Set calls set programmatic
defaults that can be overridden via command-line flags.

Signed-off-by: Pierluigi Lenoci <pierluigi.lenoci@gmail.com>

Author: pierluigilenoci

pkg/cmd/velero/velero.go

@@ -133,6 +133,9 @@ operations can also be performed as 'velero backup get' and 'velero schedule cre
 	// init and add the klog flags
 	klog.InitFlags(flag.CommandLine)
 	// Opt into fixed stderrthreshold behavior (kubernetes/klog#212).
+	// These set the programmatic defaults; users can still override via
+	// --stderrthreshold=<level> on the command line (flag parsing in
+	// cmd.Execute() runs after this).
 	_ = flag.Set("legacy_stderr_threshold_behavior", "false")
 	_ = flag.Set("stderrthreshold", "INFO")
 	c.PersistentFlags().AddGoFlagSet(flag.CommandLine)