Lewis Spurgin

@StephenAbbott - @Lathrisk put [this](https://github.com/openownership/visualisation-tool/blob/master/docs/spec.md) together (see also [this](https://github.com/openownership/visualisation-tool/pull/121) PR), which goes some way to achieving this. We should probably flag in the readme (cc @kd-ods)

The first task here is to document required fields here in a list, then we can make any easy/quick decisions about adding or removing required fields. Developing a comprehensive approach...

Just logging here that I think we might want consider this alongside issue [320](https://github.com/openownership/data-standard/issues/320) as I think that there is some confusion in (limited) existing data about how the beneficialOwnershipOrControl...