Add a Makefile target to publish on the server

Makefile

@@ -1,5 +1,9 @@
 .DEFAULT_GOAL := help
 
+include .env
+
+SERVER_OUTPUT = $(MF_GALLERY_OUTPUT) # user@server.url:/path/to/website
+
 .PHONY: install
 install: ## Install the dependencies to build the website
 	pip3 install --user -r requirements.txt
@@ -16,6 +20,11 @@ clean: ## Clean output files
 serve: build ## Serve the website (development)
 	cd output && python3 -m http.server 8080
 
+.PHONY: publish
+publish: build  ## Publish the website online (rsync)
+	echo $(SERVER_OUTPUT)
+	rsync -P -rvzc --cvs-exclude --delete ./output/ $(SERVER_OUTPUT)
+
 .PHONY: help
 help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'