Fix docstring

Makefile

@@ -40,5 +40,5 @@ migrations: ## Make migrations to the wagtail bakery site
 migrate: ## Migrate the wagtail bakery site migrations
 	docker-compose exec web python manage.py migrate
 
-test: ## Run all wagtail tests or pass in a file with `make test file=wagtail.admin.tests.test_name.py`
+test: ## Run all wagtail tests or pass in a file with `make test file=wagtail.admin.tests.test_name`
 	docker-compose exec -w /code/wagtail web python runtests.py $(file) $(FILE)