Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Tag SDNVPN for Fraser 6.0"
  - Tag SDNVPN for Fraser 6.0

    This is tagged at the current tip of stable/fraser branch

    Change-Id: Ie169aa7e2ef7096155253aeb5c8adeeefc2cf278
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 3a30f64..179812a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 3a30f64b1ccf991756500a0ca874b3ce36357dc8
+Subproject commit 179812a5ae89a8221643f8e21be110d6d38c52a2