Use consistent casing in help message

help:

	@echo  'Cleaning targets:'

	@echo  '  clean		  - remove most generated files but keep the config and'

	@echo  '  clean		  - Remove most generated files but keep the config and'

	@echo  '                    enough build support to build external modules'

	@echo  '  mrproper	  - remove all generated files + config + various backup files'

	@echo  '  mrproper	  - Remove all generated files + config + various backup files'

	@echo  '  distclean	  - mrproper + remove editor backup and patch files'

	@echo  ''

	@echo  'Configuration targets:'