Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "[centos jump] Add more missing required packages"
  - [centos jump] Add more missing required packages

    - gcc is required for NBD kernel module build;
    - gdisk is required for resizing rootfs in nbd-mounted chroot;

    Change-Id: I8863c126b75ce3a15998c03d2d159f53f5006f5d
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index a9d3798..6771512 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit a9d37983b3796adbcd0e2099487b9d14f6484e1d
+Subproject commit 6771512ac2a9402e61976140d1f0cef6d8944cf9