Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Build functest-xtesting images

    Build and push xtesting images
    Create manifests for xtesting images
    Build xtesting images for arm

    JIRA: FUNCTEST-948

    Change-Id: I3fbe6cdfef5b304a45d76533417f3c4bc58dddbe
    Signed-off-by: Delia Popescu <delia.popescu@enea.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a402cba..7862b47 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a402cbaba57fad9d0319187158fe152a3c0e503a
+Subproject commit 7862b47133a7ec4f85cb8b3a1b8ea7452fe41bc1