Use consistent casing in help message

Signed-off-by: NSamuel Tardieu <sam@rfc1149.net>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Makefile

@@ -1100,9 +1100,9 @@ boards := $(notdir $(boards))
 
 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:'