Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "xci: Make centos job non-voting for promotion"
  - xci: Make centos job non-voting for promotion

    verify-centos jobs do not vote for patch verification since
    things on centos are still shaky. Make merge-centos jobs
    non-voting for promotion as well by not allowing them to
    fail the entire promotion job or by stopping the promotion.

    Change-Id: Idf7b3c7586d94454ff94cd0bccf42f02954c722c
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>