Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - lib.sh: modprobe br_netfilter, don't bail on err

    Some sysadmins or distro defaults might blacklist br_netfilter, or
    it might not be loaded at deploy start, account for these corner
    cases too.

    JIRA: FUEL-334

    Change-Id: I3ca6cb3848df8d2af1625ff4e3816efe8b320886
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 6acecf3..ec234a8 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 6acecf3b104a072c60d071364344b9ff04994168
+Subproject commit ec234a839dbd5eb8c615e1f6a3e34db64ef1c988