Update git submodules

* Update docs/submodules/releng from branch 'master'
  - xci: Change cinder backend and move nfs to compute00

    This change
    - switches cinder backend from lvm to nfs as examplified in [1].
    - moves nfs shares from compute01 to compute00 in order to merge
    configure-targethosts.yml playbook in upcoming change.
    - updates openstack_user_config.yml to reflect the switch to nfs
    and move of nfs server to compute00.
    - removes exports file due to switching to lineinfile module.

    [1] https://docs.openstack.org/project-deploy-guide/openstack-ansible/draft/app-config-prod.html

    Change-Id: I0715c98a89ab124256e3857c1047e374f261e39b
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 86f7308..8f9a532 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 86f730857639949a2bb5135ae6366d00da424002
+Subproject commit 8f9a53258a858b78229974cf09a3da67608ef0bd