Update git submodules

* Update docs/submodules/releng from branch 'master'
  to e6f9bf8d6400b4709ff52a9ea8a23a44b292bdd0
  - Disable Airship jobs

    Intel POD 17 agent is down on purpose [1].

    [1] https://build.opnfv.org/ci/computer/intel-pod17/

    Change-Id: I6f95acdaecfbe22e3bd4f299027471c1e6627ad2
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 83b904f..e6f9bf8 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 83b904f546561f8042616109b503a473fbfe2ea7
+Subproject commit e6f9bf8d6400b4709ff52a9ea8a23a44b292bdd0