Move Monarch Ingest docs over to merge with the Monarch App docs

[sagehrke]

• Move all pages on https://monarch-initiative.github.io/monarch-ingest/ over to https://monarch-app.monarchinitiative.org/
  • Source docs will come from modularized ingest repos
  • "landing" page should have a nice description of what is in the doc site
• Review content of merged site and update to ensure accuracy.
• Add Neo4J documentation tab in https://monarch-app.monarchinitiative.org/ monarch-documentation#88
• Add new tab in https://monarch-app.monarchinitiative.org/ that links out to Monarch R docs monarch-documentation#87
• Provide a documentation page for LICENSE recommendations in Monarch monarch-documentation#79
• Once all updates are complete, don't forget to update https://monarchinitiative.org/kg/documentation