Improve Kanboard mounts

Having each folder listed as volumes individually causes issues. "Invalid mount config" in "docker stack ps kanboard"

manuscript/recipes/kanboard.md

@@ -65,8 +65,7 @@ services:
   kanboard:
     image: kanboard/kanboard
     volumes:
-     - /var/data/kanboard/data:/var/www/app/data
+     - /var/data/kanboard:/var/www/app/
-     - /var/data/kanboard/plugins:/var/www/app/plugins
     networks:
     - internal
     deploy: