Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "Rotate keystone fernet keys on shared filesystem"
  - Rotate keystone fernet keys on shared filesystem

    Change-Id: I38def56c2f276eca61f12558a03aa2693cc032f3
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index bb08806..0872be9 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit bb08806ccec36590d326627bac6cee94d3eb1e9c
+Subproject commit 0872be9745b6cd4f0e99b518c55a7824ec04a2c7