Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - Uplifting docs to D-2

    Change-Id: I8824d0620be1fff1786ed401c78062e96ca7df52
    Signed-off-by: Nikolas Hermanns <nikolas.hermanns@ericsson.com>
    (cherry picked from commit 19ff2816a46f1c4828ea104bbe0361e2d5b93ba5)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 5eded7b..9b058c2 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 5eded7bd29cd9100e70c9211a9cbc4914cf2ddf6
+Subproject commit 9b058c2eba119369d847a383ae7c0656273ee284