Consider adding '_vocabulary' global attributes for all of our vocabulary-constrained attributes

[mwengren]

For IOOS Metadata Profile 1.3:

Similar to the approach in the OceanGliders 1.0 format (OG 1.0), we might want to add _vocabulary suffixes to the global attributes in the IOOS Metadata Profile that reference an external vocabulary explicitly.

At the moment, in IOOS 1.2 this only affects creator_sector which points explicitly to the IOOS 'sector' vocabulary on the MMISW site: https://mmisw.org/ont/ioos/sector.

Other changes to make:

• If we were to add contributor_sector and publisher_sector recommended attributes per Add contributor_sector and publisher_sector as recommended fields #33, we should also include corresponding _vocabulary attributes for those as well for consistency.
• Add a URL/default vocabulary to the description for the instrument_vocabulary attribute here.
• Add a URL to the NERC CF Standard Name vocabulary (or to an example Standard Name term such as sea_water_temperature as cited in the example) to the geophysical_variable:standard_name_url description in the Variables attribute table. Standard Name vocabulary references are a little weird in the profile because we follow ACDD in our standard_name_vocabulary attribute guidance and require a text description rather than a URL and use the variable-specific standard_name_url attribute for the actual URL reference.

[mwengren]

xref re: adding vocabulary references to the _country attributes in particular: #35 (comment). If we were to implement this suggestion, we would:

• add creator_country_vocabulary and publisher_country_vocabulary attributes
• update both creator_county and publisher_country attribute descriptions to reference their respective vocabulary attributes
• identify a default vocabulary to use in each

I don't know if there's enough benefit to making all of these changes and lengthening the metadata profile attribute list even further.

Also, if we add vocabulary references for the _country attributes, why not _state as well? Also, does a 'state' or state|province|etc vocabulary exist somewhere?