Setup unified documentation

[Decipher]

Is your feature request related to a problem? Please describe.
As all packages are now in the mono-repo, the documentation needs to be updated for the mono-repo.

Describe the solution you'd like

• Update README; Provide links, resource, features, etc.
• Docgen / API Docs integration; re-write Druxt Docgen as script. #137
• [Docs] Add Nuxt site #150
• Merge in Guide content #174
• Update Guide content #175
• Update all packages README's #269

Describe alternatives you've considered
N/A

Additional context

[Decipher]

Marking this issue closed, there are other followup issue open as required.