Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [virtual] Update openstack version to pike

    Change-Id: I1df0228cb44bf9122aaf93dd25fc16a0d26a5240
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 0cd4332..8726a0d 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 0cd4332f168052af8887d794b16efa7ba661d509
+Subproject commit 8726a0d7ed8286d1aa86523a4acf61d9d4b4c9cd