Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Merge "Gather logs only if fuel or apex installer"
  - Gather logs only if fuel or apex installer

    Change-Id: I11988ad86a916d1d7251aacf951c6362fda961ba
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 66f4fcf..cd6a598 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 66f4fcfc64ed884b5adb2e78447b44ec0639fc6c
+Subproject commit cd6a598f8e0c18820783d0b0e9d3135fa833d826