[PATCH] kbuild: add kernelrelease to 'make help'

Dunno if there was a conscious decision to leave it out, but if you're
happy with adding some help text for it here's a patch against 2.6.13-mm1..

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 2402430..0d0576a 100644
--- a/Makefile
+++ b/Makefile
@@ -1053,6 +1053,7 @@
 	@echo  '  rpm		  - Build a kernel as an RPM package'
 	@echo  '  tags/TAGS	  - Generate tags file for editors'
 	@echo  '  cscope	  - Generate cscope index'
+	@echo  '  kernelrelease	  - Output the release version string'
 	@echo  ''
 	@echo  'Static analysers'
 	@echo  '  buildcheck      - List dangling references to vmlinux discarded sections'