Moved releasenotes from tempest package to proper location

* releasenotes should go under releasnotes directory. But
  add-return-value-to-retype-volume-a401aa619aaa2457.yaml was under
  tempest package. It should be moved to its proper home for
  maintaining consistency.

Change-Id: Ibfc7650bcd2e7cba17db1c2a3f6fe29131bec6de
1 file changed