Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 399a6ac546d7a4c40c4de7191563a5d23406d24a
  - Remove neutron_trunk in Airship and CIRV gates

    Else it would always fail until endpoints are fixed (pagination)

    Change-Id: Ib5c41ce7f6bc2c59d51d440da2d9eb96b7c9ed71
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 7629cef..399a6ac 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 7629cefc3a6f08b1253f58bf70dfb745992281c2
+Subproject commit 399a6ac546d7a4c40c4de7191563a5d23406d24a