docs: Add multi-region deployment documentation

I would like to see in the documentation how Temporal could efficiently scale to consistently offer it's service to clients in multiple regions and how such setup would look like.
(If it's even possible yet?)

Beside others multiple decisions for Temporal have to be made for such a deployment.

• multi region storage backend deployment and locality awareness
  • additions to db tables in CockroachDB's case
  • e.g. CockroachDB Geo-partitioning & Follower Reads, in which case we would need to add PARTITIONs to CRDB tables
  • consistency trade-offs (e.g. when doing Follower Reads)

Additional context
I strongly consider using Temporal in my organization but one strong requirement is to support multiple regions (especially with CockroachDB as storage backend) to service local clients within low latency.

No repository files or tests are named. Start by determining whether Temporal currently supports multi-region deployments, then review the linked CockroachDB geo-partitioning and follower-read material; done means documenting the supported setup, storage considerations, and consistency trade-offs.