Modify make help target for macOS (#27)

Makefile

@@ -165,4 +165,4 @@ endif
 
 # Help documentatin à la https://marmelab.com/blog/2016/02/29/auto-documented-makefile.html
 help:
-	@cat Makefile | grep -v '\.PHONY' |  grep -v '\help:' | grep -B1 -E '^[a-zA-Z_.-]+:.*' | sed -e "s/:.*//" | sed -e "s/^## //" |  grep -v '\-\-' | tac | awk 'NR%2{printf "\033[36m%-30s\033[0m",$$0;next;}1' | sort
+	@cat Makefile | grep -v '\.PHONY' |  grep -v '\help:' | grep -B1 -E '^[a-zA-Z_.-]+:.*' | sed -e "s/:.*//" | sed -e "s/^## //" |  grep -v '\-\-' | sed '1!G;h;$$!d' | awk 'NR%2{printf "\033[36m%-30s\033[0m",$$0;next;}1' | sort