Update CHANGELOG.md to reflect the promotion of 2.1.6

Obvious fix; these changes are the result of automation not creative thinking.

CHANGELOG.md

@@ -1,28 +1,25 @@
 # mixlib-cli Changelog
 
-<!-- latest_release 2.1.6 -->
-## [v2.1.6](https://github.com/chef/mixlib-cli/tree/v2.1.6) (2019-12-22)
-
-#### Merged Pull Requests
-- Substitute require for require_relative [#76](https://github.com/chef/mixlib-cli/pull/76) ([tas50](https://github.com/tas50))
+<!-- latest_release -->
 <!-- latest_release -->
 
-<!-- release_rollup since=2.1.5 -->
-### Changes not yet released to rubygems.org
-
-#### Merged Pull Requests
-- Substitute require for require_relative [#76](https://github.com/chef/mixlib-cli/pull/76) ([tas50](https://github.com/tas50)) <!-- 2.1.6 -->
+<!-- release_rollup -->
 <!-- release_rollup -->
 
 <!-- latest_stable_release -->
+## [v2.1.6](https://github.com/chef/mixlib-cli/tree/v2.1.6) (2020-04-07)
+
+#### Merged Pull Requests
+- Substitute require for require_relative [#76](https://github.com/chef/mixlib-cli/pull/76) ([tas50](https://github.com/tas50))
+<!-- latest_stable_release -->
+
 ## [v2.1.5](https://github.com/chef/mixlib-cli/tree/v2.1.5) (2019-12-22)
 
 #### Merged Pull Requests
 - Use our standard rakefile [#68](https://github.com/chef/mixlib-cli/pull/68) ([tas50](https://github.com/tas50))
 - Fix chef-style [#71](https://github.com/chef/mixlib-cli/pull/71) ([vsingh-msys](https://github.com/vsingh-msys))
 - Add windows PR testing with Buildkite [#73](https://github.com/chef/mixlib-cli/pull/73) ([tas50](https://github.com/tas50))
 - Test on Ruby 2.7 + random testing improvements [#75](https://github.com/chef/mixlib-cli/pull/75) ([tas50](https://github.com/tas50))
-<!-- latest_stable_release -->
 
 ## [2.1.1](https://github.com/chef/mixlib-cli/tree/2.1.1) (2019-06-10)