Specify a way to include DataCrate version info in CATALOG.html

[ptsefton]

Work out how to express this in RDFa, document it and add to samples.

BagIt-Profile-Identifier:
https://raw.githubusercontent.com/UTS-eResearch/datacrate/develop/spec/0.1/profile-datacrate-v0.1.json
DataCrate-Specification-Identifier:
https://github.com/UTS-eResearch/datacrate/blob/develop/spec/0.1/data_crate_specification_v0.1.md

[ptsefton]

This is very old and still no solved, putting in to the feature backlog.