Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Adding mpolenchuk@mirantis.com to committers list

    Change-Id: I973810e55ea24ba879fd91ac47388d52d43867e2
    Signed-off-by: agardner <agardner@linuxfoundation.org>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index a15eb22..7b4fbdd 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit a15eb22a56fff954ec1f7ce829a7b24eb18e42c9
+Subproject commit 7b4fbdd9be1a234c345b21ebf0eafcf7f5187f26