Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Get back to the GA kernel

    - openvswitch 2.8 officially supports kernel versions from 3.10 to 4.12
    - ODL baremetal scenario is acting up with floating/public SNAT
      flow under hwe edge kernel 4.13

    Change-Id: I099d528b3b1c2ea34f8f856cd60f809f90defea6
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index b408063..d06bcfb 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit b408063db5cd6ffca41325dae5f7f5e03c4ffb78
+Subproject commit d06bcfb72c44b507c3efee4de00f415869f48450