Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [docs] Update guest OS support matrix

    Re-testing the supported operating systems for the guests
    revealed that Fedora is now working without problems or user input
    on aarch64.

    Change-Id: I87dcac2d3297b7a43dd252d4aecfdea4254e519b
    Signed-off-by: Charalampos Kominos <Charalampos.Kominos@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 3663d63..cc7a243 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 3663d63fdd1d85a02e2b428820861ac2b194129c
+Subproject commit cc7a243c76b851dc6532433b564f99b1d6ce13c2