Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Merge "Add the xci_overrides file"
  - Add the xci_overrides file

    We can override variables by default using this file. One of those variables
    is the VM_MEMORY_SIZE

    Change-Id: I19f12151a65e90399e1ffcfa2465256bc5376abe
    Signed-off-by: Manuel Buil <mbuil@suse.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index deca6d3..9681f40 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit deca6d35cd4ba0c6444b92d15b07ade1169d0ef3
+Subproject commit 9681f405a83f93dba8a3455ee2b601ac4188a392