kbuild: small update of allnoconfig description

'allnoconfig' is described by 'make help' as a "minimal config", that's not
strictly correct. To be pedantic, a minimal config would be one where
EMBEDDED was set to Y and most things therein disabled etc. Simply
answering 'no' to all options does not give a minimal config.
A better description of allnoconfig is that it answers all options with 'no'.

This patch updates the description.
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

scripts/kconfig/Makefile

@@ -78,7 +78,7 @@ help:
 	@echo  '  defconfig	  - New config with default answer to all options'
 	@echo  '  allmodconfig	  - New config selecting modules when possible'
 	@echo  '  allyesconfig	  - New config where all options are accepted with yes'
-	@echo  '  allnoconfig	  - New minimal config'
+	@echo  '  allnoconfig	  - New config where all options are answered with no'
 
 # ===========================================================================
 # Shared Makefile for the various kconfig executables: