docs: remove production references

When you [build the documentation](https://invenio.readthedocs.io/en/latest/quickstart/final-steps.html#documentation), the integrated documentation references a production system:


It should be noted, that it's not suitable for production. It's just showing a full setup.

Start with the linked documentation build instructions and inspect the integrated documentation shown there. Update the production reference so it clearly says the setup is a full example and is not suitable for production; done when the built documentation no longer presents it as a production system.

Written by the indexing model from the issue text.