Update git submodules

* Update docs/submodules/releng from branch 'master'
  to ab5ad58dee26138d22f88f25ec542e5aa8b3eed7
  - Exclude xtesting-mts operations out of master

    https://build.opnfv.org/ci/view/xtesting/job/xtesting-hunter-daily/596/

    Change-Id: I49857bd0879425756d390f8486b1266a250749b7
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index f8ef2e2..ab5ad58 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit f8ef2e2114b472456e308d2e0bf977c3b9dcc0db
+Subproject commit ab5ad58dee26138d22f88f25ec542e5aa8b3eed7