Create demodata for templates

Description

We added a new API to create demo data.
This API can be ed to create a preview after installing QUIQQER.

Please create some demodata for the templates by using the new API.
You can find some instructions here. and here

Tasks

• Create demodata.xml for templates
• Take notes when you have problems understanding the XML file, so we can improve the documentation
• Take notes, if you are mising features in the API that we need to add