Add format command in Makefile

Makefile

@@ -13,6 +13,7 @@ help:
 	@printf "Please use 'make <target>' where '<target>' is one of:\n\n"
 	@echo "   clean                 to run ldocclean + testclean + workshopclean"
 	@echo "   dev                   to run reinstall + ldoc + lint + testclean + test"
+	@echo "   format                to run code formatting (prettier + stylua)"
 	@echo "   gitrelease            to commit modinfo.lua and CHANGELOG.md + add a new tag"
 	@echo "   install               to install the mod"
 	@echo "   ldoc                  to generate an LDoc documentation"
@@ -39,6 +40,8 @@ clean: ldocclean testclean workshopclean
 
 dev: reinstall ldoc lint testclean test
 
+format: prettier stylua
+
 gitrelease:
 	@echo "Latest Git tag: ${GIT_LATEST_TAG}"
 	@echo "Modinfo version: ${MODINFO_VERSION}\n"