Revert change so help is printed on stdout again

Fixes #1002
For backwards compatibility reasons, and to follow the need of
kubernetes/kubernetes#26077 (comment)
the help message should be printed on stdout.

Signed-off-by: Marc Khouzam <marc.khouzam@gmail.com>

command.go

@@ -372,7 +372,7 @@ func (c *Command) HelpFunc() func(*Command, []string) {
 	}
 	return func(c *Command, a []string) {
 		c.mergePersistentFlags()
-		err := tmpl(c.OutOrStderr(), c.HelpTemplate(), c)
+		err := tmpl(c.OutOrStdout(), c.HelpTemplate(), c)
 		if err != nil {
 			c.Println(err)
 		}