Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Return back repo with glusterfs

    Glusterfs 3.11 package from UCA repo has the bug#875651, which
    causes package instalation error due to timeout of glustereventsd
    service startup. Therefore get the latest version from PPA repo.

    Change-Id: Ia47d969e758c8689508dfd6b7fd2725514ea88c5
    Co-Authored-By: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index f1f85fd..8d4c328 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit f1f85fdbd111e3b2adea6e8a4185f3e50f92a02f
+Subproject commit 8d4c3285d86ece6a25609ccb207ac5fb903d1d28