*_vocabulary should point to terms instead of collection ?

[vturpin]

This has been raised in the PR #218

This issue aim to bring consistancy in the way we link users to controlled vocabulary and in the way we allow m2m approach.

I think we should guide the user the to controlled vocabulary collection, but in the data file the attribute should be the uri to the term and not the collection.
This is unclear at the moment in the document.

I suggest we clarify this by adding an attribute called *_vocabulary_collection that would be the link to the collection.

This should be applicable to all the controlled vocab that are mandatory : PLATFORM_MODEL, PLATFORM_MAKER, SENSOR_MODEL, SENSOR_TYPE, SENSOR_MAKER, PARAM

ex:
PLATFORM_MAKER:platform_maker_vocabulary_collection: https://vocab.nerc.ac.uk/collection/B75/current/ ?
PLATFORM_MAKER:platform_maker_vocabulary: https://vocab.nerc.ac.uk/collection/B75/current/ORG01077/" ?

Maybe I am wrong thinking that our reference to controlled vocabulary is unclear at the moment.

[vturpin]

addressed in PR #233