Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Enable IPv6 back for proxy/nginx node

    Change-Id: I2af8a06f5637238c4512b5a117d899fec7cb2e50
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 44497fa..bb08806 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 44497faea2b2eda0d42c8f95bd3883f68f5f35b8
+Subproject commit bb08806ccec36590d326627bac6cee94d3eb1e9c