Aerosol optical properties/MACv2-SP metadata

[znichollscr]

Metadata for the data being discussed in #124

Suggestion for the source ID and associated metadata

    "G-UHD-SPv2-1-0":{
        "contact":"<stephanie's email address>",
        "further_info_url":"www.tbd.invalid",
        "institution_id":"G-UHD",
        "license_id":"CC BY 4.0",
        "mip_era":"CMIP6Plus",
        "source_version":"1.0"
    }

Immediate comments:

• this is two institutes (GEOMAR and University of Heidelberg), hence we probably need to register a consortium
  • we'll need a new ID for GEOMAR, as the only currently registered one is locked to the marine sciences group
  • I think this is the right Heidelberg uni: https://ror.org/038t36y30. There is no Heidelberg already registered in the CMIP CMOR table repo (https://github.com/PCMDI/mip-cmor-tables/tree/main/JSONLD/organisations/institutions)
• need to double check email address