Update git submodules

* Update docs/submodules/releng from branch 'master'
  - bug fix: bad path on auto generated documentation

    bad path fix on https://gerrit.opnfv.org/gerrit/#/c/39141/

    Change-Id: Ieb8023aa7fde620c2e6b755b8e6255d2281f7a90
    Signed-off-by: Morgan Richomme <morgan.richomme@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index f21b646..6b7293d 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit f21b646f8d2045179230c18a301b6e12699d4e80
+Subproject commit 6b7293d1c19c084071bfd9d4af16a7b7fdc15930