Update git submodules

* Update docs/submodules/fuel from branch 'stable/fraser'
  - [Horizon] Drop the obsolete Horizon workaround

    Since we switch the Horizon package from
    Ubuntu/UCA repo to MCP repos,  we can drop the
    obsolete Horizon workaround.

    JIRA: FUEL-374

    Change-Id: I0b77a4f2158a972a5eb400919f2929c7bd8360cf
    Signed-off-by: ting wu <ting.wu@enea.com>
    (cherry picked from commit 63b712d1d2052e9dd762a20184913d6394f45ea9)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index b1f2be6..e668512 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit b1f2be631eb5c2622beae350b992aa034885cd7c
+Subproject commit e6685124258ed9d1237acf9d8b383c07f1397f93