Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Vagrantfile: Bump memory requirements to 16G

    Apparently 8G is no longer enought to deploy the 'mini'
    flavor since the following error occurs:

    [14505.101254] Out of memory: Kill process 23666 (qemu-system-x86) score 344 or sacrifice child
    [14505.103404] Killed process 23666 (qemu-system-x86) total-vm:5566132kB, anon-rss:3008288kB, file-rss:0kB, shmem-rss:0kB

    Change-Id: Iaa21ad367c63bf17a2c999082b5e09fa2e772d67
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index ab3ebc4..9740c63 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit ab3ebc4334b95f13948bac197bb145ef7b846890
+Subproject commit 9740c63ede4d2d804dcfdb25d80804abc924b20e