[VOL-5009] Update release notes, jira tickets.

release_notes/legend_onos_matrix.rst
release_notes/legend_voltha_matrix.rst
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  o Added legend page for ONOS and VOLTHA release matrix.
  o Document column usage.

release_notes/voltha_2.12.rst
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  o Update more published version strings.
  o VOLTHA Column labels to be less verbose.
  o Remove column 'Component Ver' as unsued.
  o Add convenience links for column headers Go(lang) and Pypi.
  o Alphabetize VOLTHA table by component name.
    Prior sort was in hierarchy/build order, more difficult to find items.

Change-Id: I66c976a113266121de173a1483f847c9ec732016
4 files changed