create SHACL definition

[rlzijdeman]

A SHACL definition of this model can be used to describe the model and to validate input data.

[wxwilcke]

Hi Richard,

This is no longer relevant with the latest release since users can adjust or supply a data model template that fits their data. Validation only made sense before when we needed to be sure it was suitable for BurgerLinker, and validating the data as a feature of its own is not the task of BurgerLinker.