Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Merge "Add Labels"
  - Add Labels

    Labels serve as refs when referenced
    from other documents.

    Change-Id: I37b93bae1283d2ea8638fc49c0c40fe7badf61ad
    Signed-off-by: ShubhamRathi <shubhamiiitbackup@gmail.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 66d5110..5ac4720 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 66d5110ec9e2fd504bc31a11592196b9d742c188
+Subproject commit 5ac4720011b78fc3878004b974c60d834cf40314