Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - I would like to nominate Georg Kunz to become a committer in the Dovetail
    project. Georg's nomination is motivated by his commitment to the project
    and his high quality work in helping the Dovetail sdnvpn test suite development,
    test doc patch review and meeting participations.

    I would like to nominate Zenghui to become a committer in the Dovetail
    project. Zenghui's nomination is motivated by his commitment to the
    project and his contributions in dovetail tool and multi-SUT testing.

    I would like to nominate Wanglei to become a committer in the Dovetail
    project. Wanglei's nomination is motivated by his commitment to the project
    and his consistent long time contribution to the Dovetail test framework
    development, test suite patch review and meeting participations.

    I would like to nominate Lincoln to become a committer in the Dovetail
    project. Lincoln's nomination is motivated by his commitment to the project
    and his expertise in multi-vendor testing, compliance testing and test doc
    patch review and meeting participations.

    I would like to nominate Trevor Cooper to become a committer in the Dovetail
    project. Trevor's nomination is motivated by his commitment to the project
    and his experiences in the testing working group, performance testing and
    consistent contributions in reviews and meeting participations.

    I would like to nominate Fuqiao to become a committer in the Dovetail project.
    Fuqiao's nomination is motivated by her commitment to the project and her
    contributions in developing the high availability test area, her experiences
    in bringing service provider requirements and perspective, and her
    contributions in reviews and meeting participations.

    Change-Id: Ia8a4ed3af7219c5376e0dd281ed11a51059c6fd4
    Signed-off-by: Wenjing Chu <chu.wenjing@gmail.com>