Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Create Xtesting stable/fraser"
  - Create Xtesting stable/fraser

    Xtesting is not directly part of Fraser but this stable branch could
    be required for bugfixes.

    stable/pike could have been selected instead but it would have raised
    side effects when syncing requirements or building containers.

    Change-Id: I407f651ba09e27a7c87cc76f7b8ccbd6c0784a48
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 2d21063..1fd4969 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 2d21063f73d9d949ffdd31ec2c0412516f83e1a6
+Subproject commit 1fd4969f08389027803eb8b137698751b200737b