Update git submodules

* Update docs/submodules/releng from branch 'master'
  to b974be779970907b5670682fca7509fdb50bd914
  - Fix node opnfv -> opnfv-build

    Change-Id: I898941fe52b60d4fc574cc837e802208badecc98
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index d7fd1f3..b974be7 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit d7fd1f34a0fcce115e8b8a2c57f0634228dc04e6
+Subproject commit b974be779970907b5670682fca7509fdb50bd914