Update changelog for Zulip 1.4.3 release.

Author: timabbott

docs/changelog.md

@@ -4,6 +4,9 @@ All notable changes to the Zulip server are documented in this file.
 
 ### Unreleased
 
+### 1.4.3 - 2017-01-29
+- CVE-2017-0881: Users could subscribe to invite-only streams.
+
 ### 1.4.2 - 2016-09-27
 - Upgraded Django to version 1.8.15 (with the Zulip patches applied),
   fixing a CSRF vulnerability in Django (see