kconfig: Add testconfig into make help output

Signed-off-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/kconfig/Makefile

@@ -149,6 +149,7 @@ help:
 	@echo  '  kvmconfig	  - Enable additional options for kvm guest kernel support'
 	@echo  '  xenconfig       - Enable additional options for xen dom0 and guest kernel support'
 	@echo  '  tinyconfig	  - Configure the tiniest possible kernel'
+	@echo  '  testconfig	  - Run Kconfig unit tests (requires python3 and pytest)'
 
 # ===========================================================================
 # Shared Makefile for the various kconfig executables: