story #6377 - have ranked chart legend

Change-Id: I1d040936be1e8c63526004a81e4ffbcf464a194c
Merge commit 'refs/changes/33/2033/4' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #6377 - have ranked chart legend

Change-Id: Ie87b353ab40570933fa76170acb04386f7b64bfb
This is Tuleap 6.11.99.7

Change-Id: I1f13de96bd7178fa7d79a360f0cd94e1a3cdfdb4