Add warning to make-update and make-push

Add warning before make-update and make-push to alert developers that
running the commands might be destructive. Allow cancelling the command
up to 3 seconds before continuing. Also explain that merge conflicts
warrant a re-run of the command.

Makefile

@@ -9,14 +9,20 @@ include .gitlab/make/helm.makefile
 include .gitlab/make/kaniko.makefile
 include .gitlab/make/truenas.makefile
 
+.PHONY: warning
+warning:
+	@printf "Running a potentially destructive command. If a conflict occurs, fix the conflict and re-run the command.\n"
+	@printf "Cancel with ctrl + c within 3 seconds."
+	@sleep 3
+
 .PHONY: make-update
-make-update:
+make-update: warning
 	@git stash
 	-git subtree pull --prefix .gitlab git@gitlab.ducoterra.net:services/common.git main --squash
 	@if [-z "$(shell git stash list)"; then git stash pop; fi;
 
 .PHONY: make-push
-make-push:
+make-push: warning
 	@make make-update
 	@git remote add common git@gitlab.ducoterra.net:services/common.git
 	@git subtree push --prefix .gitlab common main