This is a continous attempt at an overview of tier-1/user-facing infrastructure. It will likely never be complete from all POV, but.. it is more accurate and complete than it has been. Thanks to all that contributed by entertaining my many questions over the years.
Notable changes:
* Add new Drmrs data center in Marseille, France.
* Add new services: purged.go, EventStreams, Thumbor, mcrouter, Envoy, etcd.
* Add new distinction for Multi-DC between primary and secondary data center.
* Change sessionstore from Redis to Kask/Cassandra.
* Change jobqueue from Redis to EventGate/Kafka.
* Include distinct MediaWiki server roles and clusters.
* Include high-level MediaWiki platform components.
* Include example flow for "JobQueue job" and "CDN purge".