WIP: nomenclature

[joehand]

This DEP is still work-in-progress.

I've added the summary/motivation and Bryan's questions. I need to put a bit of thought in how to best organize this, in the case we have a lot of terms in here.

We also have existing terms in the Dat documentation: https://docs.datproject.org/terms. I can update/consolidate those to this DEP.

I will try to collect some good examples of other nomeclature/naming convention docs as motivation, if you have suggestions.