Wrong message appears in Collection when you have an empty database

[pablodiegoss]

Describe the bug When you run Jandig in a development environment that you haven`t created any content yet the collection page displays the wrong message. To reproduce the bug

1. Delete your jandig db or run Jandig in a new environment
2. Run Jandig with Docker-compose up
3. Access localhost:8000 on your pc
4. Click on Collection
5. The message that appears is "This element isn't being used yet. :("

Expected behavior The message should say something about no user content added yet or that your db got an empty collection, just to make it clearer for new developers that are running a new environment, since this message won`t ever show up in production where we already have contents uploaded.

Screenshots