clarify the statement on usage for HVD datasets

[NielsHoffmann]

This is an issue from the GeoDCAT-AP 3.0.0 pilot.

The readme of the repository contains a short explanation on the usage of the XSLT for High-Value Datasets.
It states that 'this XSLT, or its output, needs to be adjusted', without going into detail what this means.

Since there is an effort being made to align the way we describe HVD information in the ISO Profile, it would be good to expand the explanation on the XSLT whether this transformation is 'on the roadmap' to be implemented in the XSLT or not.
Or, at the minimum, provide an outline what organisations would need to do to implement HVD transformation in the XSLT.

I think we need to come to a common re-usable approach to be able to create high quality metadata.