Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "[centos jump] Add missing dependency for nbd build"
  - [centos jump] Add missing dependency for nbd build

    Change-Id: Icb23d2e6d3bb6e49b54e2d51cc8a35cb03702fcd
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 5878c5c..252fd2b 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 5878c5c0c2ca8c78e9a5124452eefe8290ab63cd
+Subproject commit 252fd2b6fe32a77a4014ce33ead9f77817b1d2c9