Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - removing multiple labels

    Change-Id: I28fe4db7598c20ca7be90bc7cd57bf0d9770847b
    Signed-off-by: Nikolas Hermanns <nikolas.hermanns@ericsson.com>
    (cherry picked from commit 036dc38f8ffc4353c15d6b42658a2236b41702f7)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 2b4934d..d78cde7 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 2b4934d59544b307e8847cb77ff6948c8ba67f7d
+Subproject commit d78cde76782fef27af8b26e81781e3c74158a5ce