GARD / MedGen: Update & remove: configs, docs, & refs

[joeflack4]

Overview

We won't be ingesting these like we do with other sources. They will be doing mapping work to Mondo. So we should remove any / most existing setup / code we have for these sources.

We should

• [ ] Docs: Update
  • [ ] Remove the "normal", autogenerated docs for GARD/Medgen
  • [ ] Add a page that clearly explains how GARD, MedGen, ClinGen and NORD are going to be imported moving forward
• [ ] Remove: configs in metadata/
• [ ] Remove refs (goals, etc)

[joeflack4]

Closed this PR as consequence:

• 360