Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [baremetal] Return back custom image for vcp nodes

    Virtual node based on cloud ubuntu image
    won't register as a minion on salt master.

    Change-Id: Ia32eae01a5633042189cdebebcba8043cae61503
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 7fb1944..5f4ea4e 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 7fb1944d93e16365acd0792069b1229fc5964670
+Subproject commit 5f4ea4eae484a37d1a41e1f5e235285fafccbbe7