Update git submodules

* Update docs/submodules/fuel from branch 'stable/fraser'
  - Revert "[patch] Backport proposed generate_dhparams fix"

    This reverts commit c7dff6e1ae6444f60d3fe20b1f495609c7980051.
    The patch has been merged into upstream.

    Change-Id: Idf768b9b94b3498994601d50feeeef008430ba27
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>
    (cherry picked from commit 7b358ba97fce7925ea6504977ae1c600e3123e3c)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index f6ad9dc..504f00b 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit f6ad9dcea662e54217878693921e14e4158412bf
+Subproject commit 504f00b570186664be8f16a52aa19075f9b25841