command: hard wrap help message flags

This greatly improves readability when lots of flags are registered.

Signed-off-by: Ophestra <cat@gensokyo.uk>

command/builder.go

@@ -23,8 +23,8 @@ func newNode(output io.Writer, logf LogFunc, name, usage string) *node {
 	n.set.SetOutput(output)
 	n.set.Usage = func() {
 		_ = n.writeHelp()
-		if n.suffix.Len() > 0 {
-			_, _ = fmt.Fprintln(output, "Flags:")
+		if len(n.suffix) > 0 {
+			_, _ = fmt.Fprintln(output, "flags:")
 			n.set.PrintDefaults()
 			_, _ = fmt.Fprintln(output)
 		}