Update git submodules

* Update docs/submodules/container4nfv from branch 'stable/gambia'
  - add scenarior for virlet and kata

    Change-Id: I24eaa36693b05343f67a3a777d04b7841dca9884
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>
    (cherry picked from commit 554a84f03e586252c5f0fc320acd046a2ae93439)

diff --git a/docs/submodules/container4nfv b/docs/submodules/container4nfv
index 1fa07ef..97f02fd 160000 (submodule)
--- a/docs/submodules/container4nfv
+++ b/docs/submodules/container4nfv
@@ -1 +1 @@
-Subproject commit 1fa07ef952a6b0e12487901919cec52b9d9b9739
+Subproject commit 97f02fd3d2168135d9837926c0515b3d5b8de6ad