Update git submodules

* Update docs/submodules/fuel from branch 'stable/fraser'
  - [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>
    (cherry picked from commit cc7a243c76b851dc6532433b564f99b1d6ce13c2)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index c8dcc5d..f6ad9dc 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit c8dcc5d5dd821120dbe8320ab5adc805ff6ea5c2
+Subproject commit f6ad9dcea662e54217878693921e14e4158412bf