Instructions for adding new loci

[hdashnow]

We need a guide to adding new loci (and potentially to updating existing ones). It should cover:

• How to assess evidence for pathogenicity
• What data should be included in STRchive (including minimum for a new locus)
• Technically how to add/update a locus
  Probably one or more checklists would do the job.

The schema I started here might be useful for some aspects of this: #126

We can brainstorm specifics here, or start a shared doc.