update CHANGELOG

CHANGELOG.md

@@ -80,6 +80,8 @@ BUG FIXES:
   * builder/docker: Fix crash that could occur at certain timed ctrl-c [GH-1838]
   * builder/docker: validate that `export_path` is not a directory [GH-2105]
   * builder/google: `ssh_timeout` is respected [GH-1781]
+  * builder/openstack: `ssh_interface` can be used to specify the interface
+      to retrieve the SSH IP from. [GH-2220]
   * builder/qemu: Add `disk_discard` option [GH-2120]
   * builder/virtualbox: Bind HTTP server to IPv4, which is more compatible with
       OS installers. [GH-1709]