Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[dovetail] disable Dovetail jobs on master"
  - [dovetail] disable Dovetail jobs on master

    As Cedirc suggested, Dovetail should only run in Installers' Gambia jobs because
    Dovetail now integrates Functest Gambia.
    Disable Dovetail master jobs.

    Change-Id: Id39993801b6f98e77fc1a86f4c099b01bcfa8770
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 99cb177..c6f7b5e 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 99cb17791659b1602263c82d26e21d175c99e8c7
+Subproject commit c6f7b5e81eeb261160a4c412828b464e3fa7d414