kbuild: add 'includecheck' help text

Add 'includecheck' to the Static analyzers help list.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -1188,6 +1188,7 @@ help:
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
 	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
+	@echo  '  includecheck    - Check for duplicate included header files'
 	@echo  '  export_report   - List the usages of all exported symbols'
 	@if [ -r $(srctree)/include/asm-$(SRCARCH)/Kbuild ]; then \
 	 echo  '  headers_check   - Sanity check on exported headers'; \