Update git submodules

* Update docs/submodules/ipv6 from branch 'master'
  - Update document framework for Gambia release

    Change-Id: I500a3ece02f12c96c00c0194e24a53117e269089
    Signed-off-by: BIN HU <bh526r@att.com>

diff --git a/docs/submodules/ipv6 b/docs/submodules/ipv6
index 294c135..6deace1 160000 (submodule)
--- a/docs/submodules/ipv6
+++ b/docs/submodules/ipv6
@@ -1 +1 @@
-Subproject commit 294c135cb87b12df8491c068972a02464dc33dfc
+Subproject commit 6deace1abcae9479868bf99f527f839da825b269