Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [centos jump] nbd build: Fix REQ_TYPE_SPECIAL

    Change-Id: Ia514418d2aae1b4f7e752d4610fa6c9829c67e51
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 924d481..84f5818 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 924d481ac84e8fad9bf1132e1cff18967887017e
+Subproject commit 84f58189f269be6633e0c8897d5624d3dfaaa650