Expand create accelerator tutorial #38

The create accelerator tutorial is not so easy to understand if you haven't first read some of the other parts of the documentation despite that this tutorial is likely the entry point for most new users.

It needs to be expanded with more details. This can be links to other pages but ideally also some sentences directly in the tutorial to explain the basic concepts.

The type field in the configuration example also needs to be changed to class to not confuse the users since type is supposed to be removed eventually.