README: throughput number in v3, add Doorman

Our v3 benchmark shows etcd v3 can do 40k writes per second.
1k throughput number is for etcd v2. Also adds YouTube's doorman
to example project lists.

README.md

@@ -15,17 +15,18 @@ etcd is a distributed, consistent key-value store for shared configuration and s
 
 * *Simple*: well-defined, user-facing API (gRPC)
 * *Secure*: automatic TLS with optional client cert authentication
-* *Fast*: benchmarked 1000s of writes/s per instance
+* *Fast*: benchmarked 40,000 writes/sec per instance
 * *Reliable*: properly distributed using Raft
 
 etcd is written in Go and uses the [Raft][raft] consensus algorithm to manage a highly-available replicated log.
 
-etcd is used [in production by many companies](./Documentation/production-users.md), and the development team stands behind it in critical deployment scenarios, where etcd is frequently teamed with applications such as [Kubernetes][k8s], [fleet][fleet], [locksmith][locksmith], [vulcand][vulcand], and many others.
+etcd is used [in production by many companies](./Documentation/production-users.md), and the development team stands behind it in critical deployment scenarios, where etcd is frequently teamed with applications such as [Kubernetes][k8s], [fleet][fleet], [locksmith][locksmith], [vulcand][vulcand], [Doorman][doorman], and many others.
 
 See [etcdctl][etcdctl] for a simple command line client.
 
 [raft]: https://raft.github.io/
 [k8s]: http://kubernetes.io/
+[doorman]: https://github.com/youtube/doorman
 [fleet]: https://github.com/coreos/fleet
 [locksmith]: https://github.com/coreos/locksmith
 [vulcand]: https://github.com/vulcand/vulcand