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/block/Kconfig b/drivers/block/Kconfig
index a4a3119..ef32e97 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -6,6 +6,12 @@
 	bool "Block devices"
 	depends on BLOCK
 	default y
+	---help---
+	  Say Y here to get to see options for various different block device
+	  drivers. This option alone does not add any kernel code.
+
+	  If you say N, all options in this submenu will be skipped and disabled;
+	  only do this if you know what you are doing.
 
 if BLK_DEV