Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 5eb0aa6925a3b77acc88fae1550c76a6dedd1fde
  - Switch back to lf-build6

    lf-build6 is back.

    Change-Id: Id66ea36cc97ba77e32d82dc526568baea3502b95
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 2b5bfa7..5eb0aa6 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 2b5bfa7888cc2e0d2553a1ead6cdff643743f13a
+Subproject commit 5eb0aa6925a3b77acc88fae1550c76a6dedd1fde