Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - Uplifting docs to D-3

    Change-Id: Iff2f924886bae8e4bf84f4325cde3d7f8546b487
    Signed-off-by: tomsou <soth@intracom-telecom.com>
    (cherry picked from commit 82a6d6e756177273c94f64e675bf196989479028)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index d4061ae..58a0249 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit d4061aeface0d67ea0e038359c7c61e9482cad85
+Subproject commit 58a0249ab01b1c66c71bc402a6ea7f53e34b6c35