Update git submodules

* Update docs/submodules/fuel from branch 'stable/fraser'
  - [salt-formulas] opendaylight: Adjust keyserver prx

    Align opendaylight/server sls with the latest salt-formula-linux
    version of keyserver requests support behind proxy.

    Change-Id: I55f9010eec8b74932d4a28215ecf9647deb3d82c
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 6924fe7e4cadeb5dbe6857adb413d688209bd4e1)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 4ad7bc8..f848787 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 4ad7bc825848153f38e321588e597f34d1472d6f
+Subproject commit f84878774000718216dfb0575a55a63c03c2b39d