* Adds Deployment Guide and update links
* Fixes releases link
* Re-organisation of content
* Cuts down "deployment" doc (which should focus on Reference Architecture) by moving raft and performance tuning to the Server Performance page which already covers some of this.
* Moves backups from "deployment" doc (which should focus on Reference Architecture) to "deployment-guide"
* Cleans up some notes and add single DC diagram
* Removes old link to deployment guide from nav
* Corrects minor styling, formatting, and grammar
* Adds XL machine spec and notes on large deployments
* Clarifies machine sizes
* Fixes internal links within the document
* Moves datacenter size guidelines to "Single Datacenter" section
Erik R. Rygg