kbuild: document versioncheck in make help

	@echo  'Static analysers'

	@echo  '  checkstack      - Generate a list of stack hogs'

	@echo  '  namespacecheck  - Name space analysis on compiled kernel'

	@echo  '  versioncheck    - Sanity check on version.h usage'

	@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 \