Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Download 3 extra images and remove modification of fuel openrc file"
  - Download 3 extra images and remove modification of fuel openrc file

    1. Download 3 extra images for functest snaps_smoke and cloudify_ims
    2. Remove the modification of fuel openrc file because of this patch has
       added a function to check cacert file
       https://gerrit.opnfv.org/gerrit/#/c/52021/

    Change-Id: I2cab3bf11231d5d6ad39dca6d2d833355b1e6679
    Signed-off-by: xudan <xudan16@huawei.com>