Update git submodules

* Update docs/submodules/apex from branch 'stable/danube'
  - Merge "Workaround for vhost-user binding" into stable/danube
  - Workaround for vhost-user binding

    This is a workaround for this bug:
    https://bugs.launchpad.net/networking-odl/+bug/1696968

    JIRA: APEX-475

    Change-Id: Ic115e094c2906d6572d6af411872d5584e665aec
    Signed-off-by: juraj.linkes <jlinkes@cisco.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 9d3f55f..4411a14 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 9d3f55f994988e1443e7d3316045238595730d1d
+Subproject commit 4411a144af0f5b817f9c280713edaa5eab73b2f0