Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Add list of releng openstack contributions"
  - Add list of releng openstack contributions

    - All the contributions listed in this file are merged commits.
    - Contributions under review, in progress and abandoned are not included.
    - The latest contribution included in this file is 453130 and it is dated
    2017-05-23.
    - Contributions from Yolanda Robla Mota have not been included yet.
    - The gerrit query used to list contributions is
        status:merged AND (owner: "Markos Chandras" OR owner: "Fatih Degirmenci")

    Change-Id: Iee927cbd883419ce2d6506178725cd90bd9b21b6
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>