Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 2b5bfa7888cc2e0d2553a1ead6cdff643743f13a
  - Switch to lf-build5

    lf-build6 is down

    Change-Id: Ib3929fe4f236533b6743516af26249ffaef08c07
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 7c53866..2b5bfa7 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 7c538667c383f7fadf124f114ad995c64bf7c670
+Subproject commit 2b5bfa7888cc2e0d2553a1ead6cdff643743f13a