Update git submodules

* Update docs/submodules/releng from branch 'master'
  to b4dc52223022a31506bc9201f5cd98f1088a6dd0
  - Merge "Remove odl and juju_epc"
  - Remove odl and juju_epc

    Change-Id: I77569d72b0d7bd63b0eed817aade57ad8534bb4c
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a4b164d..b4dc522 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a4b164d8b10be199627d9e5e913b190f0e7d98b2
+Subproject commit b4dc52223022a31506bc9201f5cd98f1088a6dd0