Horizon 2.x docs refresh

[jcx120]

What problem does your feature solve?

Refresh of Horizon public docs to provide details and clarity on installation, topology, infra reqs etc.

What would you like to see?

Areas that need updates and new sections:

• [x] primary installation guide
• [x] topology view of key options (new)
  • [x] developer
  • [x] small - medium deployment
  • [x] Enterprise nTier
• [x] tabular breakdown of spec reqs based on needs (new)
• [x] Update Ingestion guide. Remove spec references, point to Prereq page
• [ ] Operator guide (maintenance, tuning, operational best practices) (new)
• [ ] FAQ - common issues & solutions (new)

Update:

• [ ] Running Horizon in Production
• [ ] verify docker references are to correct one

[jcx120]

@Shaptic any other sections to include?