Updates the change log for advanced autopilot and network areas.

CHANGELOG.md

@@ -15,6 +15,9 @@ FEATURES:
   - **Dead Server Cleanup:** Dead servers will periodically be cleaned up and removed from the Raft peer set, to prevent them from interfering with the quorum size and leader elections.
   - **Server Health Checking:** An internal health check has been added to track the stability of servers. The thresholds of this health check are tunable as part of the [Autopilot configuration](https://www.consul.io/docs/agent/options.html#autopilot) and the status can be viewed through the [`/v1/operator/autopilot/health`](https://www.consul.io/docs/agent/http/operator.html#autopilot-health) HTTP endpoint.
   - **New Server Stabilization:** When a new server is added to the cluster, there will be a waiting period where it must be healthy and stable for a certain amount of time before being promoted to a full, voting member. This threshold can be configured using the new [`server_stabilization_time`](https://www.consul.io/docs/agent/options.html#server_stabilization_time) setting.
+  - **Advanced Redundancy:** (Consul Enterprise) A new [`-non-voting-server`](https://www.consul.io/docs/agent/options.html#_non_voting_server) option flag has been added for Consul servers to configure a server that does not participate in the Raft quorum. This can be used to add read scalability to a cluster in cases where a high volume of reads to servers are needed, but non-voting servers can be lost without causing an outage. There's also a new [`redundancy_zone_tag`](https://www.consul.io/docs/agent/options.html#redundancy_zone_tag) configuration that allows Autopilot to manage separating servers into zones for redundancy. Only one server in each zone can be a voting member at one time. This helps when Consul servers are managed with automatic replacement with a system like a resource scheduler or auto-scaling group. Extra non-voting servers in each zone will be available as hot standbys (that help with read-scaling) that can be quickly promoted into service when the voting server in a zone fails.
+  - **Upgrade Orchestration:** (Consul Enterprise) Autopilot will automatically orchestrate an upgrade strategy for Consul servers where it will initially add newer versions of Consul servers as non-voters, wait for a full set of newer versioned servers to be added, and then gradually swap into service as voters and swap out older versioned servers to non-voters. This allows operators to safely bring up new servers, wait for the upgrade to be complete, and then terminate the old servers.
+* **Network Areas:** (Consul Enterprise) A new capability has been added which allows operators to define network areas that join together two Consul datacenters. Unlike Consul's WAN feature, network areas use just the server RPC port for communication, and pairwise relationships can be made between arbitrary datacenters, so not all servers need to be full connected. This allows for complex topologies among Consul datacenters like hub/spoke and more general trees.
 * **WAN Soft Fail:** Request routing between servers in the WAN is now more robust by treating Serf failures as advisory but not final. This means that if there are issues between some subset of the servers in the WAN, Consul will still be able to route RPC requests as long as RPCs are actually still working. Prior to WAN Soft Fail, any datacenters having connectivity problems on the WAN would mean that all DCs might potentially stop sending RPCs to those datacenters. [GH-2801]
 * **WAN Join Flooding:** A new routine was added that looks for Consul servers in the LAN and makes sure that they are joined into the WAN as well. This catches up up newly-added servers onto the WAN as soon as they join the LAN, keeping them in sync automatically. [GH-2801]
 * **Validate command:** To provide consistency across our products, the `configtest` command has been deprecated and replaced with the `validate` command (to match Nomad and Terraform). The `configtest` command will be removed in Consul 0.9. [GH-2732]