Include directory creation optimization in changelog

Author: tjcelaya

CHANGELOG.md

@@ -10,6 +10,10 @@ This project aims to adhere to [Semantic Versioning](http://semver.org/).
    to response headers as `x-load-balancer`. The header will be injected into the response if it is not already present.
  - Azul Systems' [Zulu JDK](https://www.azul.com/products/zulu-and-zulu-enterprise/)
    has been [added to the Travis-CI test matrix](https://github.com/joyent/java-manta/pull/382).
+ - [Recursive directory creation](https://github.com/joyent/java-manta/issues/371)
+   can now attempt to skip a configurable number of levels in order to avoid redundant `PUT` requests. See
+   `manta.skip_directory_depth` / `MANTA_SKIP_DIRECTORY_DEPTH` in the configuration documentation for an explanation
+   of how the optimization can be enabled.
 ### Fixed
  - [Signing of URLs which need to be encoded](https://github.com/joyent/java-manta/issues/379) has been fixed.
  - [Java 9](https://github.com/joyent/java-manta/pull/382) compatibility improvements.