Updated CHANGELOG for 0.24.0-rc2.

Updated CHANGELOG for 0.24.0-rc2.

Added a comment in Perf to explain kill correctness.

Review: https://reviews.apache.org/r/37424

Updated CHANGELOG for 0.23.0-rc4

Updated CHANGELOG for 0.23.0-rc4

Updated CHANGELOG for 0.23.0-rc3

Updated CHANGELOG for 0.23.0-rc2

Review: https://reviews.apache.org/r/36295

Updated CHANGELOG for 0.23.0.

Copied in contents of JIRA Release Notes, categorized.

Review: https://reviews.apache.org/r/36152

Updated CHANGELOG for 0.22.1-rc6 again, added MESOS-2461.

Updated CHANGELOG for 0.22.1-rc6 again, added MESOS-2461.