Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [mcp] Mend networks config

    * create openstack/neutron external network
    * set default gateway for mgmt network

    Change-Id: I71c22ab6d1b8c589c1cf147aa37874600ab1cbd7
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 5b6ef48..f2a8139 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 5b6ef486ab10ed93d5212daa64edeb59cd2c71ff
+Subproject commit f2a813931b01e29783eb927e5962a920a1ada27e