Follow-up from "Improve capitalization in geo and HA docs"

The following discussions from !16879 (merged) should be addressed:

@eread started a discussion:

This issue is now closed, because of Single codebase transition. Can we find a better link?

The trade-off is between reducing server counts, against the increased operational complexity of needing to deal with PostgreSQL [failover](#failover-procedure) and [restore](#restore-procedure) procedures in addition to [Consul outage recovery](consul.md#outage-recovery) on the same set of machines.