Updated 1.0 CHANGELOG about MESOS-5389.

Review: https://reviews.apache.org/r/50367
diff --git a/CHANGELOG b/CHANGELOG
index 9f67057..2e1b363 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -352,6 +352,7 @@
     * [MESOS-5382] - Implement os::fsync
     * [MESOS-5383] - Implement os::setHostname
     * [MESOS-5386] - Add `HANDLE` overloads for functions that take a file descriptor
+    * [MESOS-5389] - docker containerizer should prefix relative volume.container_path values with the path to the sandbox.
     * [MESOS-5390] - v1 Executor Protos not included in maven jar
     * [MESOS-5397] - Slave/Agent Rename Phase 1: Update terms in the website
     * [MESOS-5403] - Introduce ObjectApprover Interface to Authorizer.