doc: bootdelay: drop explanation about CONFIG_BOOTDELAY from README

The same information now exists in common/Kconfig.  Do not duplicate
documentation from the point of view of maintainability.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>

README

@@ -890,23 +890,6 @@ The following options need to be configured:
 		'Sane' compilers will generate smaller code if
 		CONFIG_PRE_CON_BUF_SZ is a power of 2
 
-- Boot Delay:	CONFIG_BOOTDELAY - in seconds
-		Delay before automatically booting the default image;
-		set to -1 to disable autoboot.
-		set to -2 to autoboot with no delay and not check for abort
-		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
-
-		See doc/README.autoboot for these options that
-		work with CONFIG_BOOTDELAY. None are required.
-		CONFIG_BOOT_RETRY_TIME
-		CONFIG_BOOT_RETRY_MIN
-		CONFIG_AUTOBOOT_KEYED
-		CONFIG_AUTOBOOT_PROMPT
-		CONFIG_AUTOBOOT_DELAY_STR
-		CONFIG_AUTOBOOT_STOP_STR
-		CONFIG_ZERO_BOOTDELAY_CHECK
-		CONFIG_RESET_TO_RETRY
-
 - Autoboot Command:
 		CONFIG_BOOTCOMMAND
 		Only needed when CONFIG_BOOTDELAY is enabled;

common/Kconfig

@@ -168,6 +168,8 @@ config BOOTDELAY
 	  set to -2 to autoboot with no delay and not check for abort
 	  (even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
 
+	  See doc/README.autoboot for details.
+
 config CONSOLE_RECORD
 	bool "Console recording"
 	help