Enforce a standard such as SI for unit of measure notations (symbols)

[jordanbrauer]

I think it would be a good idea to enforce a standard for unit symbols. This would mean that there is a common ground for understanding what unit is being used based on context.

Reference the two attached .pdf files for the list of accepted SI unit symbols (we should put this in the docs/readme/contribution guide).

Links:
commonly used metric system units symbols and prefixes

Attachments:
abbreviation.pdf
sp811.pdf