Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Add Gerrit Trigger on Tag Creation"
  - Add Gerrit Trigger on Tag Creation

    We should be able to capture a tag creation event by triggering on
    'ref-updated' but looking specifically at the 'refs/tags/' branch
    prefix.

    Though this will trigger a build against a specific tag, scripts will
    still need to examine the GERRIT_REFSPEC to determine the tag name.

    Change-Id: Ic18a3e11530fb71735431240f93d2074dacf4e1c
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>