Add some help texts to recently-introduced kconfig items

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (edited MACINTOSH_DRIVERS per Geert Uytterhoeven's remark)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index 7dd7354..63436892 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -6,6 +6,9 @@
 	bool "USB support"
 	depends on HAS_IOMEM
 	default y
+	---help---
+	  This option adds core support for Universal Serial Bus (USB).
+	  You will also need drivers from the following menu to make use of it.
 
 if USB_SUPPORT