QPID-5764: add note detaling the move to the maven build for future releases, to be merged to 0.28 branch

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1594176 13f79535-47bb-0310-9956-ffa450edef68
QPID-5764: update note to reflect the trunk maven build no longer requiring flag to enable

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1594177 13f79535-47bb-0310-9956-ffa450edef68