Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - xci: roles: bootstrap-host: Simplify configuration files

    We split the networking task on distro specific files to make it
    easier to read. Moreover, the debian network configuration has been
    improved by simply sharing a common file across all nodes and also
    use the 'source' facility in the main /etc/network/interfaces file
    to use one configuration file per interface.

    Change-Id: Ic822fe6dc197227e70c0ba7cee812629df287d82
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index be67faf..15be5eb 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit be67faf1cfaeb2f0d1ff73c90c8b3996b2b6a506
+Subproject commit 15be5eb8da9881428ea1635a3184c39f63dfaf80