Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/gambia'
  - Update release date

    Change-Id: I10d30cf5be8370676813c1501c0ed73e189d19c2
    Signed-off-by: dimitris.tsiolakis <dmts@intracom-telecom.com>
    (cherry picked from commit 63ea4922aa8340e2d6ffde0cce3ddff775900f15)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 07de5b7..6c2ec2e 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 07de5b7295d72bf0db2872494c91295b677b9238
+Subproject commit 6c2ec2eeedfc342e815b3dff7c190d8909e22e48