Adds a note about the new go-cleanhttp behavior to the change log.

CHANGELOG.md

@@ -1,5 +1,17 @@
 ## 0.7.0 (UNRELEASED)
 
+BACKWARDS INCOMPATIBILITIES:
+
+* The Consul API client is now configured to disable connection reuse and idle
+  connections to the Consul server, meaning it can potentially make a new connection
+  for every API method that's called. Previously, idle connections were supported
+  and their lifetime was managed by a finalizer, but this wasn't reliable in certain
+  situations. If you don't reuse your API client object, then there's nothing to do.
+  If you have a long-lived API client object, you may want to configure it using the
+  `DefaultPooledTransport` so it will reuse a single connecetion to Consul. Here's an
+  [example from Vault](https://github.com/hashicorp/vault) showing how to do this.
+  [GH-1731]
+
 IMPROVEMENTS:
 
 * Consul agents will now periodically reconnect to available Consul servers