Clarify the definition of `representation technique`

[jakubklimek]

Problem statement
The definition of representation technique currently says:

More information about the format in which an Asset Distribution is released. This is different from the file format as, for example, a ZIP file (file format) could contain an XML schema (representation technique).

However, talking here about a ZIP file (package) containing an XML schema inside seems confusing in the context of DCAT-AP Distribution Packaging Format, which would normally be used (for ZIP) together with media type (for XML schema) for this type of scenario.

This was identified in SEMICeu/GeoDCAT-AP#97.

Proposal
Change the definition simply to:

More information about the format in which an Asset Distribution is released.