[epic] Make Data Rich Docs site

[rufuspollock]

• Refactor to be data rich documents spec and site #17
• Make front page nicer - can draw from https://github.com/datahubio/datarich-app
  • Add hero
  • Add image demo side by side
• Add back examples e.g. climate data one #18
• Add tutorials - see https://github.com/datahubio/datarich-app/tree/main/content/docs