add update target to Makefile

Makefile

@@ -3,5 +3,11 @@
 help: ## Show all Makefile targets
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
 
-serve: ## serve
+update: ## Update Quartz to the latest version on Github
+	@git remote show upstream || (echo "remote 'upstream' not present, setting 'upstream'" && git remote add upstream https://github.com/jackyzha0/quartz.git)
+	git fetch upstream
+	git log --oneline --decorate --graph ..upstream/hugo
+	git checkout -p upstream/hugo -- layouts .github Makefile assets/js assets/styles/base.scss assets/styles/darkmode.scss config.toml data 
+
+serve: ## Serve Quartz locally
 	hugo-obsidian -input=content -output=assets/indices -index -root=. && hugo server --enableGitInfo